托福阅读TPO24(试题+答案+译文)第:BreathingDuringSleep

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篇1：托福阅读TPO24(试题+答案+译文)第:BreathingDuringSleep

托福阅读原文

【1】Of all the physiological differences in human sleep compared with wakefulness that have been discovered in the last decade, changes in respiratory control are most dramatic. Not only are there differences in the level of the functioning of respiratory systems, there are even changes in how they function. Movements of the rib cage for breathing are reduced during sleep, making the contractions of the diaphragm more important. Yet because of the physics of lying down, the stomach applies weight against the diaphragm and makes it more difficult for the diaphragm to do its job. However, there are many other changes that affect respiration when asleep.

【2】During wakefulness, breathing is controlled by two interacting systems. The first is an automatic, metabolic system whose control is centered in the brain stem. It subconsciously adjusts breathing rate and depth in order to regulate the levels of carbon dioxide (CO2) and oxygen (O2), and the acid-base ratio in the blood. The second system is the voluntary, behavioral system. Its control center is based in the forebrain, and it regulates breathing for use in speech, singing, sighing, and so on. It is capable of ignoring or overriding the automatic, metabolic system and produces an irregular pattern of breathing.

【3】During NREM (the phase of sleep in which there is no rapid eye movement) breathing becomes deeper and more regular, but there is also a decrease in the breathing rate, resulting in less air being exchanged overall. This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less oxygen and produces less carbon dioxide. Also, during sleep the automatic metabolic system is less responsive to carbon dioxide levels and oxygen levels in the blood. Two things result from these changes in breathing control that occur during sleep. First, there may be a brief cessation or reduction of breathing when falling asleep as the sleeper waxes and wanes between sleep and wakefulness and their differing control mechanisms. Second, once sleep is fully obtained, there is an increase of carbon dioxide and a decrease of oxygen in the blood that persists during NREM.

【4】But that is not all that changes. During all phases of sleep, several changes in the air passages have been observed. It takes twice as much effort to breathe during sleep because of greater resistance to airflow in the airways and changes in the efficiency of the muscles used for breathing. Some of the muscles that help keep the upper airway open when breathing tend to become more relaxed during sleep, especially during REM (the phase of sleep in which there is rapid eye movement). Without this muscular action, inhaling is like sucking air out of a balloon—the narrow passages tend to collapse. Also there is a regular cycle of change in resistance between the two sides of the nose. If something blocks the “good” side, such as congestion from allergies or a cold, then resistance increases dramatically. Coupled with these factors is the loss of the complex interactions among the muscles that can change the route of airflow from nose to mouth.

【5】Other respiratory regulating mechanisms apparently cease functioning during sleep. For example, during wakefulness there is an immediate, automatic, adaptive increase in breathing effort when inhaling is made more difficult (such as breathing through a restrictive face mask). This reflexive adjustment is totally absent during NREM sleep. Only after several inadequate breaths under such conditions, resulting in the considerable elevation of carbon dioxide and reduction of oxygen in the blood, is breathing effort adjusted. Finally, the coughing reflex in reaction to irritants in the airway produces not a cough during sleep but a cessation of breathing. If the irritation is severe enough, a sleeping person will arouse, clear the airway, then resume breathing and likely return to sleep.

【6】Additional breathing changes occur during REM sleep that are even more dramatic than the changes that occur during NREM. The amount of air exchanged is even lower in REM than NREM because, although breathing is more rapid in REM,it is also more irregular, with brief episodes of shallow breathing or absence of breathing. In addition, breathing during REM depends much more on the action of the diaphragm and much less on rib cage action.

托福阅读试题

1.According to paragraph 1, which of the following can be inferred about the diaphragm during sleep?

A.During sleep the diaphragm requires increased movement of the rib cage.

B.The diaphragm helps with breathing as movements of the rib cage decrease during sleep.

C.The diaphragm requires a great amount of pressure to function properly.

D.The diaphragm contributes to the effective functioning of the rib cage.

2.According to paragraph 2, all of the following are true of the voluntary breathing system EXCEPT:

A.It has its control center in the brain stem.

B.It controls breathing for a number of activities during wakefulness.

C.It is able to bypass the automatic system.

D.It produces an irregular breathing pattern.

3.The word exclusive in the passage (paragraph 3) is closest in meaning to

A.consistent

B.perfect

C.partial

D.sole

4.According to paragraph 3, which of the following may occur just before NREM sleep begins?

A.The automatic, metabolic system may increase its dependence on air exchanges.

B.Breathing can stop for a short time as a person falls asleep.

C.An increase in the oxygen level in the blood can occur as sleep becomes fully obtained.

D.The level of carbon dioxide in the blood may drop suddenly.

5.What is the author's purpose in stating that inhaling is like sucking air out of a balloon?(in paragraph 4)

A.To refute the argument that additional effort is necessary for breathing during sleep.

B.To argue that REM sleep is more important than NREM sleep.

C.To illustrate the difficulty of breathing during sleep.

D.To illustrate how blockage of narrow passages can be prevented during sleep.

6.All of the following are mentioned in paragraph 4 as being characteristic of breathing during sleep EXCEPT

A.relaxation of the muscles involved in the respiratory system.

B.changes in resistance between the two sides of the nose.

C.easier airflow in the passages of the upper airway.

D.absence of certain complex muscle interactions.

7.According to paragraph 5, what happens during NREM sleep when inhaling is difficult?

A.There is an immediate, automatic, adaptive increase in breathing effort.

B.The sleeping person takes several inadequate breaths before the breathing effort is adjusted.

C.The coughing reflex causes the breathing effort to adjust.

D.The airways become cleared as the blood removes irritants.

8.It can be inferred from paragraph 5 that a very mild irritation during sleep will likely cause the sleeping person to

A.increase the breathing effort.

B.wake up and remove the source of irritation.

C.cough while still sleeping.

D.stop breathing temporarily while still sleeping.

9.The word considerable (paragraph 5)meaning to

A.significant.

B.Steady.

C.Usual.

D.necessary.

10.The word resume in the passage (paragraph 5) is closest in meaning to

A.reduce.

B.stop.

C.readjust.

D.restart.

11.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage (paragraph 6)? Incorrect choices change the meaning in important ways or leave out essential information.

A.Because breathing is more shallow and irregular in REM than in NREM, less air is exchanged in REM.

B.Breathing in NREM is less effective than breathing in REM because of irregular episodes of rapid breathing during NREM.

C.Because breathing is more rapid in NREM sleep than in REM sleep, breathing often becomes shallow.

D.Although REM has brief episodes of shallow breathing or lack of breathing, breathing is more rapid than in NREM.

12. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? Click on a square to add the sentence to the passage. To better understand breathing during sleep, it is, however, helpful to first understand how respiration works in general.

paragraph1: Of all the physiological differences in human sleep compared with wakefulness that have been discovered in the last decade, changes in respiratory control are most dramatic. Not only are there differences in the level of the functioning of respiratory systems, there are even changes in how they function. Movements of the rib cage for breathing are reduced during sleep, making the contractions of the diaphragm more important. [■]【A】 Yet because of the physics of lying down, the stomach applies weight against the diaphragm and makes it more difficult for the diaphragm to do its job. [■]【B】 However, there are many other changes that affect respiration when asleep.

paragraph2: [■]【C】 During wakefulness, breathing is controlled by two interacting systems. [■]【D】The first is an automatic, metabolic system whose control is centered in the brain stem. It subconsciously adjusts breathing rate and depth in order to regulate the levels of carbon dioxide (CO2) and oxygen (O2), and the acid-base ratio in the blood. The second system is the voluntary, behavioral system. Its control center is based in the forebrain, and it regulates breathing for use in speech, singing, sighing, and so on. It is capable of ignoring or overriding the automatic, metabolic system and produces an irregular pattern of breathing.

13.Directions: From the seven statements below, select the statements that correctly characterize breathing during wakefulness and those statements that correctly characterize breathing during sleep. Drag each answer choice you select into the appropriate box of the table. Two of the answer choices will NOT be used. This question is worth 3 points.

A.The role of the rib cage increases and the role of the diaphragm decreases.

B.Carbon dioxide in blood rises and oxygen drops.

C.The coughing reflex is extremely complex.

D.A great deal of effort is used for breathing.

E.Upper airways are resistant to colds and allergies.

F.There is a drop in the volume of air that is exchanged.

G.Automatic and voluntary respiratory systems are both involved.

1 )

Wakefulne

A B C D E F G

2 )

Sleep

A B C D E F G

托福阅读答案

1.以diaphragm做关键词定位至第三句和第四句，说ribcage运动变少，使得diaphragm更重要，但stomach的压力使得diaphragm工作起来更困难，B是正确答案。A的increased movement of the rib cage和C的需要pressure都与原文相反;D说diaphragm contributes to原文没有说。

2.EXCEPT题，排除法。A的centered in brain stem做关键词定位至第一句，但原文说这个特点是属于automatic，metabolic system的，而voluntary的center是在forebrain，所以A错，选;B的a number of activities做关键词定位至倒数第二句的一大堆活动，所以B正确，不选;C的bypass the automatic system和D的irregular breathing pattern做关键词都定位至最后一句，都正确，不选。

3.exclusive仅有，只有，排他，所以正确答案是sole。从单词本身看，include→exclude→exclusive，所以一定能得出排他之意。原句说在NREM期间，automatic系统怎么控制breathing，使得氧的需求量减少，前面一直在说两个系统，现在氧的需求量减少了，肯定是有系统不干活了，所以就是只有automatic在干活，所以答案是D只有。A持续、B完美，都不靠谱，C的partial刚好与原文意思相反，也不选。

4.此题关键词难找，可以顺序向下看，也可以用排除法，如果顺序向下看的话，会看到第一点说的是当sleeper在睡与醒之间摇摆的时候，发生了呼吸cessation，也就是stop，所以正确答案是B，stop for a short time。C和D一个说氧上升一个说二氧化碳下降，是一回事，都不是在睡觉期间发生的，所以都反了，而且两个一样的也都不选，A没说。

5.修辞目的题，先看修辞点所在的句子，但原句整个都是一个例子，往前看。前一句仍然在说肌肉relax的事情，因此也是例子，所以看开头，开头说air passage在睡觉期间变了很多紧接着就解释睡觉期间呼吸很难，也就是开头所指的变化是睡觉的时候呼吸变难，所以正确答案是C。A的refute与原文相反;B的比较和D的prevent blockage原文都没说。

6.EXCEPT题，排除法。A的relaxation of the muscles做关键词定位至第三句，正确，不选;B的two sides of the nose做关键词定位至倒数第三句，正确，不选;C的upper airway做关键词定位至第三句，但答案的easier airflow原文完全没说，C错，选;D的complex muscle interaction做关键词都定位至最后一句，正确，不选。

7.以inhaling is difficult做关键词定位至第二句，但这句只说了difficult的事儿，没说发生了什么，往下看。下句说NREM期间什么adjustment都没有，只有在inadequate breaths之后才adjust，所以答案是B。A是wakeful时候才有的;C的因果关系原文没说;D完全没说。

8.以irritation做关键词定位至最后一句，说如果irritation太严重，睡着的人就会醒，按照正常的叙述顺序应该是先叙述mild的情况，前一句果然在说coughing reflex没产生cough，而产生了cessation of breathing，呼吸停止的状况，所以答案是D。C与原文相反;B是severe的时候才有的，A没说。

9.considerable可观的，相当的，重要的，所以正确答案是significant。从单词本身看，consider的考虑的意思是很常见的，加形容词词尾able变为值得考虑的，所以也是significant。原文说在若干次inadequate breaths之后，二氧化碳含量怎么上升氧气含量下降，才能调整breathing，一般我们说显著的变化，所以答案A，其他答案都不靠谱。

10.resume重新开始，再继续，所以正确答案是restart。原句说如果irritation太严重了，睡着的人会醒来，清理呼吸道，并且怎么呼吸，前一句都说了因为irritants呼吸停止，然后醒来，当然清理完就继续呼吸了呗，答案是D。A和B完全不靠谱，如果选C，之前应该adjust一次，但之前从来没说irritation严重的时候有先调整一次，所以C错。

11.原句的结构是exchange lower是因为blabla，所以正确答案是A，因果关系和结构都正确。其他答案都没提到exchange lower这个主干，而且B把原文非主干的部分变成了主干;C结果搞乱;D逻辑关系错。

12.两个过渡点，名词respiration和连词however。根据respiration可以初步确定答案是B或者C，但根据however断定B不对，因为两个however不能连续出现，所以正确答案是C。

13.第一段和第二段在讲wakeful部分，其余在讲sleep部分。The role选项对应第一段第三句，属于wakeful部分。Carbon dioxide选项对应第五段第四句，二氧化碳多氧少，属于sleep部分。The coughing选项原文没说reflex复杂，不属于任何一列，不选。A great deal选项对应原文第四段第三句，属于sleep部分。Upper airways选项原文没说，不选。There is选项对应原文第六段第二句，属于sleep部分。Automatic选项对应原文第二段首句，属于wakeful部分。

托福阅读译文

【1】关于人类睡觉和清醒时生理状态的差异在过去的十年里已被发现，在所有的这些差异中，呼吸系统控制方面的变化尤其引人注目。不仅是呼吸系统运作水平有差异，在如何运作方面也出现了变化。胸腔所做的呼吸运动在睡觉时会减少，使得横膈膜的收缩变得更为重要。然而由于躺下来的物理作用，胃部压迫横膈膜使得横膈膜难以工作。不管怎样，睡眠时还有很多其他的变化影响着呼吸。

【2】清醒的时候，呼吸受到两个互相影响的系统的控制。第一个是自动的新陈代谢系统，它的控制中心在脑干。它会潜意识的调整呼吸频率和深度来控制二氧化碳和氧气的浓度以及血液中的酸碱比。第二套系统是自发行为系统。它的控制中心在前脑，调节说话、唱歌、叹息等行为时的呼吸。它能忽略或无视自动新陈代谢系统并且产生无规律的呼吸模式。

【3】在NMER(睡觉时没有快速眼部活动的阶段)这个阶段中，呼吸会变得更深更有规律，但是呼吸频率会降低，导致总体空气交换减少。发生这个是因为在NREM睡眠阶段中，自动的新陈代谢系统会独自控制呼吸，身体会利用更少的氧气产生更少的二氧化碳。同时，自动的新陈代谢系统对血液中二氧化碳和氧气的含量反应并不灵敏。在睡眠中呼吸控制的变化会导致两个结果。第一，睡着时呼吸可能会有短暂的停止或减少，因为睡眠者在睡眠和清醒之间徘徊，而这两种状态的控制系统不一样。第二，一旦得到了充足的睡眠，血液中二氧化碳含量升高而氧气含量降低，在NREM阶段也会持续这样。

【4】但这并不是全部的变化。在睡眠的所有阶段中，气道的一些变化已经被观察到了。睡眠时需要付出两倍的努力去呼吸，因为呼吸道气流的阻力会比较强并且用来呼吸的肌肉的效率会有变化。一些在呼吸时帮助保持上呼吸道通畅的肌肉在睡觉的时候会变得松弛，特别是在REM阶段(就是有快速眼部运动的睡眠阶段)。没有这种肌肉运动，呼吸空气就像从气球里吸气一样，狭窄的通道会面临崩溃。而且鼻子两侧的阻力也会周期性改变。如果有时候堵塞了“好”的一边，比如过敏和感冒引起的堵塞，阻力就会大大增加。与这些因素一起的是那些能够改变从鼻子到嘴巴的气流路径的肌肉之间失去了复杂的交互。

【5】其他呼吸调节机制在睡眠时显然要停止运作。比如说，在清醒时如果呼吸变得困难的话就会有一个立即自动适应性的呼吸增强(比如戴上面具呼吸)。但在NREM状态时完全不存在这样反射性的调节。在这种情况下，只有几次不充分的呼吸后使得血液中二氧化碳的含量显著提升以及氧气的含量降低，呼吸才会被调整过来。最后，咳嗽反应在应对呼吸道中刺激物时产生的不是睡觉时咳嗽而是呼吸停止。如果刺激物足够严重，睡着的人会醒来清理气道，然后继续呼吸很可能再度入睡。

【6】发生在REM时期的多余的呼吸变化比发生在NREM时期的呼吸变化更显著。REM的空气交换量要比NREM低，因为尽管REM中呼吸更加急促，但也更加没有规律，包括一些简短的浅呼吸或呼吸暂停。另外，REM时期的呼吸更多取决于横膈膜而不是胸腔的作用。

托福阅读TPO24(试题+答案+译文)第2篇:Breathing During Sleep

篇2：托福阅读TPO20(试题+答案+译文)第:FossilPreservation

托福阅读原文

【1】When one considers the many ways by which organisms are completely destroyed after death, it is remarkable that fossils are as common as they are. Attack by scavengers and bacteria, chemical decay, and destruction by erosion and other geologic agencies make the odds against preservation very high. However, the chances of escaping complete destruction are vastly improved if the organism happens to have a mineralized skeleton and dies in a place where it can be quickly buried by sediment. Both of these conditions are often found on the ocean floors, where shelled invertebrates (organisms without spines) flourish and are covered by the continuous rain of sedimentary particles. Although most fossils are found in marine sedimentary rocks, they also are found in terrestrial deposits left by streams and lakes. On occasion, animals and plants have been preserved after becoming immersed in tar or quicksand, trapped in ice or lava flows, or engulfed by rapid falls of volcanic ash.

【2】The term “fossil” often implies petrifaction, literally a transformation into stone. After the death of an organism, the soft tissue is ordinarily consumed by scavengers and bacteria. The empty shell of a snail or clam may be left behind, and if it is sufficiently durable and resistant to dissolution, it may remain basically unchanged for a long period of time. Indeed, unaltered shells of marine invertebrates are known from deposits over 100 million years old. In many marine creatures, however, the skeleton is composed of a mineral variety of calcium carbonate called aragonite. Although aragonite has the same composition as the more familiar mineral known as calcite, it has a different crystal form, is relatively unstable, and in time changes to the more stable calcite.

【3】Many other processes may alter the shell of a clam or snail and enhance its chances for preservation. Water containing dissolved silica, calcium carbonate, or iron may circulate through the enclosing sediment and be deposited in cavities such as marrow cavities and canals in bone once occupied by blood vessels and nerves. In such cases, the original composition of the bone or shell remains, but the fossil is made harder and more durable. This addition of a chemically precipitated substance into pore spaces is termed “permineralization.”

【4】Petrifaction may also involve a simultaneous exchange of the original substance of a dead plant or animal with mineral matter of a different composition. This process is termed “ replacement” because solutions have dissolved the original material and replaced it with an equal volume of the new substance. Replacement can be a marvelously precise process, so that details of shell ornamentation, tree rings in wood, and delicate structures in bone are accurately preserved.

【5】Another type of fossilization, known as carbonization, occurs when soft tissues are preserved as thin films of carbon. Leaves and tissue of soft-bodied organisms such as jellyfish or worms may accumulate, become buried and compressed, and lose their volatile constituents. The carbon often remains behind as a blackened silhouette.

【6】Although it is certainly true that the possession of hard parts enhances the prospect of preservation, organisms having soft tissues and organs are also occasionally preserved. Insects and even small invertebrates have been found preserved in the hardened resins of conifers and certain other trees. X-ray examination of thin slabs of rock sometimes reveals the ghostly outlines of tentacles, digestive tracts, and visual organs of a variety of marine creatures. Soft parts, including skin, hair, and viscera of ice age mammoths, have been preserved in frozen soil or in the oozing tar of oil seeps.

【7】The probability that actual remains of soft tissue will be preserved is improved if the organism dies in an environment of rapid deposition and oxygen deprivation. Under such conditions, the destructive effects of bacteria are diminished. The Middle Eocene Messel Shale (from about 48 million years ago) of Germany accumulated in such an environment. The shale was deposited in an oxygen-deficient lake where lethal gases sometimes bubbled up and killed animals. Their remains accumulated on the floor of the lake and were then covered by clay and silt. Among the superbly preserved Messel fossils are insects with iridescent exoskeletons (hard outer coverings), frogs with skin and blood vessels intact, and even entire small mammals with preserved fur and soft tissue.

托福阅读试题

1.The word “agencies” in the passage (paragraph 1) is closest in meaning to

A.combinations.

B.problems.

C.forces.

D.changes.

2.In paragraph 1, what is the author's purpose in providing examples of how organisms are destroyed?

A.To emphasize how surprising it is that so many fossils exist.

B.To introduce a new geologic theory of fossil preservation.

C.To explain why the fossil record until now has remained incomplete.

D.To compare how fossils form on land and in water.

3.The word “terrestrial” in the passage (paragraph 1) is closest in meaning to

A.land.

B.protected.

C.alternative.

D.similar.

4.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage (paragraph 2)? Incorrect choices change the meaning in important ways or leave out essential information.

A.When snail or clam shells are left behind, they must be empty in order to remain durable and resist dissolution.

B.Although snail and clam shells are durable and resist dissolving, over time they slowly begin to change.

C.Although the soft parts of snails or clams dissolve quickly, their hard shells resist dissolution for a long time.

D.Empty snail or clam shells that are strong enough not to dissolve may stay in their original state for a long time.

5.Why does the author mention “aragonite” in the passage (paragraph 2)?

A.To emphasize that some fossils remain unaltered for millions of years.

B.To contrast fossil formation in organisms with soft tissue and in organisms with hard shells.

C.To explain that some marine organisms must undergo chemical changes in order to fossilize.

D.To explain why fossil shells are more likely to survive than are fossil skeletons.

6.The word “enhance” in the passage (paragraph 3) is closest in meaning to

A.control.

B.limit.

C.combine.

D.increase.

7.Which of the following best explains the process of permineralization mentioned in paragraph 3?

A.Water containing calcium carbonate circulates through a shell and deposits sediment.

B.Liquid containing chemicals hardens an already existing fossil structure.

C.Water passes through sediment surrounding a fossil and removes its chemical content.

D.A chemical substance enters a fossil and changes its shape.

8.The word “precise” in the passage (paragraph 4) is closest in meaning to

A.complex.

B.quick.

C.exact.

D.reliable.

9.Paragraph 5 suggests which of the following about the carbonization process?

A.It is completed soon after an organism dies.

B.It does not occur in hard-shell organisms.

C.It sometimes allows soft-tissued organisms to be preserved with all their parts.

D.It is a more precise process of preservation than is replacement.

10.The word “prospect” in the passage (paragraph 6) is closest in meaning to

A.completion.

B.variety.

C.possibility.

D.speed.

11.According to paragraph 7, how do environments containing oxygen affect fossil preservation?

A.They increase the probability that soft-tissued organisms will become fossils.

B.They lead to more bacteria production.

C.They slow the rate at which clay and silt are deposited.

D.They reduce the chance that animal remains will be preserved.

12.According to paragraph 7， all of the following assist in fossil preservation EXCEPT

A.the presence of calcite in an organism's skeleton.

B.the presence of large open areas along an ocean floor.

C.the deposition of a fossil in sticky substances such as sap or tar.

D.the rapid burial of an organism under layers of silt.

13. Look at the four squares [■] that indicate where the following sentence can be added to the passage. Where would the sentence best fit? Click on a square [■] to insert the sentence in the passage. But the evidence of past organic life is not limited to petrifaction. ■【A】Another type of fossilization, known as carbonization, occurs when soft tissues are preserved as thin films of carbon. ■【B】Leaves and tissue of soft-bodied organisms such as jellyfish or worms may accumulate, become buried and compressed, and lose their volatile constituents. ■【C】The carbon often remains behind as a blackened silhouette.■【D】

14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some answer choices do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. The remains of ancient life are amazingly well preserved in the form of fossils.

A.Environmental characteristics like those present on ocean floors increase the likelihood that plant and animal fossils will occur.

B.Fossils are more likely to be preserved in shale deposits than in deposits of clay and silt.

C.The shells of organisms can be preserved by processes of chemical precipitation or mineral exchange.

D.Freezing enables the soft parts of organisms to survive longer than the hard parts.

E.Comparatively few fossils are found in the terrestrial deposits of streams and lakes.

F.Thin films of carbon may remain as an indication of soft tissue or actual tissue may be preserved if exposure to bacteria is limited.

托福阅读答案

1.agency代理，中介，作用，所以答案是force，选C。原句说由于腐食动物和细菌的侵袭，化学侵蚀和其他地质什么的作用，使得保存的难度非常大。combination组合明显不靠谱，problem是个负向词，不靠谱，之前并列的都不是变化，change不对。

2.修辞目的题，修辞点所在句是一个例子，所以往前看，前一句说fossil遭破坏的方式和fossil一样多，后面就跟了很多破坏的方式，所以答案是A，阐释为什么如此多破坏之下还有这么多化石存在。往后看也可以，下一句说如果化石有骨架的话被保留的机会会大增，也就是一直都在说化石存留下来的机会，所以A是正确答案。

3.terrestrial陆地的，陆生的，所以正确答案是A。原文说尽管大部分的化石都是在海洋中找到的，但也有一些是在河湖中的什么沉积物当中找到的，既然前文都说了大部分是在海洋里找到的，肯定后面会说是在陆地上找到的，所以答案是terrestrial，B/C/D都不靠谱。

4.原句的结构是并列加条件，所以正确答案是D。A的must be empty原文没说;B和C的关系都错误;D说的是shell会被剩下，如果足够耐腐蚀，就能保存一段时间。

5.修辞目的题，先看例子所在句子，说很多海洋生物的骨骼包含calcite，没有答案，往前看，前一句说一亿年前的沉积物中能发现骨骼不变的海生无脊椎动物，与A靠谱，但A本身不是一个观点，所以A不对;B和D完全没说，不对;强调的中心在例子所在句的下一句，说arogonite的晶体形状不同，相对不那么稳定，会变成更稳定的形式，所以答案是C，想稳定的话必须再变。

6.enhance提升，提高，所以正确答案是D的increase。原文说很多化学过程都能改变壳体的结构并且怎么样它们作为化石保留下来的机会，combine明显不靠谱;limit和control意思相近，而且这两个词与increase意思相反，所以其他三个都不对。

7.以permineralization做关键词定位至最后一句。说将chemically precipitate的物质加入precipitate的过程叫做permineralization，this指代前文，所以往前看，前面说血管和神经占据的空隙会被充填，骨头和壳体会留下来，变得更坚固，所以答案是B，变得更坚硬。A的包含calcium不全面，而且原文的变硬也没说;C的remove chemical content和D的change shape都没说。

8.precise精确的，所以C 的exact正确。原文说replacement是一个非常什么样的过程，壳体的纹饰，树轮和骨架上的微细结构都被记录下来，B快和D可信完全不靠谱，细微结构被记录下来不见得复杂，所以complex也不对。

9.此段较短，完全可以快速扫完，当然用排除法也比较好。A错，原文说生命死后要经过若干过程才会carbonization，所以A的soon明显错;B正确，原文明确指出carbonization发生在柔软组织中，当然也就不会发生在硬壳动物身上;C的all their parts和D的比较原文都没说，都错。

10.prospect展望，前景，勘探，所以C 的possibility正确。原句说尽管有硬壳提高了保存下来的什么，但软体动物也能偶尔被保存下来。根据让步推出硬壳动物应该是容易保存下来，但跟保存下来的完整性和种类都无关，所以variety和completion都不对，speed完全不沾边。

11.以oxygen做关键词定位至第一句，说如果快速埋藏，并且在缺氧环境下，化石保存的概率会增加，也就是说氧的存在不利于化石的保存，所以正确答案是D，A与D刚好完全相反，所以A错，也说明两个相反的有一个对;C完全没说;B错，原文说缺氧能减轻细菌的破坏作用，但并不意味着有氧细菌就会变多，所以B没说。

12.EXCEPT题，排除法，由于考全文，应该关注各段开头。A的skeleton和calcite做关键词定位至第六段首句，正确，不选;B的ocean floor在原文中虽然有出现，但open areas没有，所以B错，选;C的sap or tar做关键词定位至第六段最后一句，正确，不选;D的rapid burial和layer of silt做关键词定位至第七段第一句，正确，不选。

13.如果找名词过渡，最容易找到的当属petrification，但遗憾的是，整段中既没有petrification，也没有同义词替换，这段段首已经开始说carbonization，也就是说petrification应该是上一段或者下一段说的，也就是A或者D正确，但待插入句说不仅限于，也就是前面已经说过petrification了，所以A对D错。

14.Environmental选项对应原文首段第三句，A正确。Fossils选项的比较原文没说，B不选。The shells选项对应原文第三段最后一句和第四段开头句，C正确。Freezing选项在原文第六段结尾捎带提了一下，但没说比较，D不选。Comparatively选项与原文第一段倒数第二句说反，E不选。The films选项对应原文第五段和第七段开头，F正确。

托福阅读译文

【1】如果想想生物在死之后被完全摧毁的种.种方式，能够这样频繁出现化石是一件很令人惊讶的事。食腐动物和细菌的破坏、化学性腐烂、腐蚀以及其它地质因素都会非常不利于保存。不过，如果生物体碰巧具有矿化的骨骼并且死于可以迅速被沉积物掩埋的地方，摆脱被完全摧毁的几率便会大大增加。海底通常就具有上述的两方面条件，这里生活着很多带壳的无脊椎动物(没有脊椎的动物)，不断累积的似雨的沉积颗粒会把它们掩埋起来。虽然多数的化石是在海洋沉积岩中发现的，但是在溪流和湖泊留下的陆相沉积物中也发现过。有时，浸入焦油和流沙、陷入冰或熔岩流或被急速降落的火山灰吞噬的动植物得以保存下来。 【2】术语“化石”常常意味着石化，字面意思就是变成了石头。生物体死后，软组织一般会被食腐动物和细菌吃掉。可能会留下蜗牛或蛤蜊空壳，如果空壳足够坚固并且能抵御分解，就有可能在很长一段时间内基本上保持原样。事实上，我们现在所知的在沉积物中发现的海洋无脊椎动物保存良好的壳已超过了1亿年之久。不过，很多海洋生物的骨骼是由称为霰石的各式碳酸钙矿物质组成的。虽然霰石与我们更为熟悉的矿物方解石具有同样的组成，但是它的晶型不同，相对不稳定，最终会变成更稳定的方解石。 【3】很多其他过程也许会改变哈喇壳或蜗牛壳并且增加它被保存下来的几率。 含有溶解的二氧化硅、碳酸钙或铁的水可能会在封闭的沉积物中流动，并沉积到诸如骨髓腔和骨头管道内，这些骨头管道曾经由血管和神经占据。这种情况下，骨和壳的原始组成没有改变，但是形成的化石更坚硬并且更持久。这种在孔隙中填充化学沉积物的过程就叫做“完全矿化”。 【4】石化还可能同时涉及死亡的动植物的原有物质与不同组成的矿物质的交换作用。该过程叫做“置换作用”，因为溶液溶解了原始物质并将其置换成为等体积的新物质。置换是一个让人难以置信的精确过程，贝壳装饰的细节、树木的年轮以及骨骼的精细结构都被精准地保存下来。 【5】另一种类型的石化，称为“碳化”，当软组织以碳薄膜的形式保存时会发生碳化。树叶和软体动物例如水母或蠕虫的组织可能会堆积起来，被掩埋并被压实，然后其中的挥发性成分会消失。碳通常以一种黑色轮廓的形式被保留下来。 【6】虽然拥有坚硬的部分的确会增加保存的可能性，但是具有软组织和器官的生物偶尔也会被保存下来。在针叶树以及某些其它的树种的凝固树脂中就发现了昆虫甚至是很小的无脊椎动物。对岩石薄片的X射线检查有时会发现可怕的触角轮廓、消化道和很多种海洋生物的视觉器官。冻土或石油渗漏时渗出的焦油中保存了包括皮肤、毛发和冰河时代猛犸象的内脏在内的软组织。 【7】如果生物体死于一个快速沉积和缺氧的环境，会有助于软组织残骸的保存。在这种条件下，细菌的破坏性影响会降低。德国始新世中期的麦塞尔页岩(来自4800万年前)就是在这种环境下积累起来的。该页岩在一个缺氧的湖泊里沉积，那里时有致命的气体冒出并杀死动物。动物的残骸在湖底聚集，然后被粘土和淤泥所覆盖。在保存完好的麦塞尔化石中有带闪亮外骨骼(硬质外部覆盖物)的昆虫，皮肤和血管完好无损的青蛙，甚至是毛皮和软组织都完整保存的小型哺乳动物。

托福阅读TPO20(试题+答案+译文)第3篇:Fossil Preservation

篇3：托福阅读TPO25(试题+答案+译文)第:ThesurfaceofMars

托福阅读原文

【1】The surface of Mars shows a wide range of geologic features, including huge volcanoes-the largest known in the solar system-and extensive impact cratering. Three very large volcanoes are found on the Tharsis bulge, an enormous geologic area near Mars’s equator. Northwest of Tharsis is the largest volcano of all: Olympus Mons, with a height of 25 kilometers and measuring some 700 kilometers in diameter at its base. The three large volcanoes on the Tharsis bulge are a little smaller-a “mere” 18 kilometers high.

【2】None of these volcanoes was formed as a result of collisions between plates of the Martian crust-there is no plate motion on Mars. Instead, they are shield volcanoes — volcanoes with broad, sloping slides formed by molten rock. All four show distinctive lava channels and other flow features similar to those found on shield volcanoes on Earth. Images of the Martian surface reveal many hundreds of volcanoes. Most of the largest volcanoes are associated with the Tharsis bulge, but many smaller ones are found in the northern plains.

【3】The great height of Martian volcanoes is a direct consequence of the planet’s low surface gravity. As lava flows and spreads to form a shield volcano, the volcano’s eventual height depends on the new mountain’s ability to support its own weight. The lower the gravity, the lesser the weight and the greater the height of the mountain. It is no accident that Maxwell Mons on Venus and the Hawaiian shield volcanoes on Earth rise to about the same height (about 10 kilometers) above their respective bases-Earth and Venus have similar surface gravity. Mars’s surface gravity is only 40 percent that of Earth, so volcanoes rise roughly 2.5 times as high. Are the Martian shield volcanoes still active? Scientists have no direct evidence for recent or ongoing eruptions, but if these volcanoes were active as recently as 100 million years ago (an estimate of the time of last eruption based on the extent of impact cratering on their slopes), some of them may still be at least intermittently active. Millions of years, though, may pass between eruptions.

【4】Another prominent feature of Mars’s surface is cratering. The Mariner spacecraft found that the surface of Mars, as well as that of its two moons, is pitted with impact craters formed by meteoroids falling in from space. As on our Moon, the smaller craters are often filled with surface matter-mostly dust-confirming that Mars is a dry desert world. However, Martian craters get filled in considerably faster than their lunar counterparts. On the Moon, ancient craters less than 100 meters across (corresponding to depths of about 20 meters) have been obliterated, primarily by meteoritic erosion. On Mars, there are relatively few craters less than 5 kilometers in diameter. The Martian atmosphere is an efficient erosive agent, with Martian winds transporting dust from place to place and erasing surface features much faster than meteoritic impacts alone can obliterate them.

【5】As on the Moon, the extent of large impact cratering (i.e. craters too big to have been filled in by erosion since they were formed) serves as an age indicator for the Martian surface. Age estimates ranging from four billion years for Mars’s southern highlands to a few hundred million years in the youngest volcanic areas were obtained in this way.

【6】The detailed appearance of Martian impact craters provides an important piece of information about conditions just below the planet’s surface. Martian craters are surrounded by ejecta (debris formed as a result of an impact) that looks quite different from its lunar counterparts. A comparison of the Copernicus crater on the Moon with the (fairly typical) crater Yuty on Mars demonstrates the differences. The ejecta surrounding the lunar crater is just what one would expect from an explosion ejecting a large volume of dust, soil, and boulders. However, the ejecta on Mars gives the distinct impression of a liquid that has splashed or flowed out of crater. Geologists think that this fluidized ejecta crater indicates that a layer of permafrost, or water ice, lies just a few meters under the surface. Explosive impacts heated and liquefied the ice, resulting in the fluid appearance of the ejecta.

托福阅读试题

1.The word “enormous”(paragraph 1)in the passage is closest in meaning to

A.important

B.extremely large

C.highly unusual

D.active

2.According to paragraph 1, Olympus Mons differs from volcanoes on the Tharsis bulge in that Olympus Mons

A.has more complex geologic features

B.shows less impact cratering

C.is taller

D.was formed at a later time

3.The word “distinctive”(paragraph 1)in the passage is closest in meaning to

A.deep.

B.complex.

C.characteristic.

D.ancient.

4.According to paragraphs 1 and 2, which of the following is NOT true of the shield volcanoes on the Tharsis bulge?

A.They have broad, sloping sides.

B.They are smaller than the largest volcano on Mars.

C.They have channels that resemble the lava channels of volcanoes on Earth.

D.They are over 25 kilometers tall.

5.The word “roughly” in the passage is closest in meaning to

A.typically.

B.frequently.

C.actually.

D.approximately.

6.In paragraph 3, why does the author compare Maxwell Mons on Venus to the Hawaiian shield volcanoes on Earth?

A.To help explain the relationship between surface gravity and volcano height.

B.To explain why Mars’s surface gravity is only 40 percent of Earth’s.

C.To point out differences between the surface gravity of Earth and the surface gravity of Venus.

D.To argue that there are more similarities than differences between volcanoes on different planets.

7.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaningin important ways or leave out essential information.

A.Although direct evidence of recent eruptions is lacking, scientists believe that these volcanoes were active as recently as 100 million years ago.

B.Scientists estimate that volcanoes active more recently than 100 years ago will still have extensive impact cratering on their slopes.

C.If, as some evidence suggests, these volcanoes erupted as recently as 100 million years ago, they may continue to be intermittently active.

D.Although these volcanoes were active as recently as 100 million years ago, there is no direct evidence of recent or ongoing eruptions.

8.The word “considerably”(paragraph 3)in the passage is closest in meaning to

A.frequently.

B.significantly.

C.clearly.

D.surprisingly.

9.According to paragraph 4, what is demonstrated by the fact that cratersfill in much faster on Mars than on the Moon?

A.Erosion from meteoritic impacts takes place more quickly on Mars than on the Moon.

B.There is more dust on Mars than on the Moon.

C.The surface of Mars is a dry desert.

D.Wind is a powerful eroding force on Mars.

10.In paragraph 4, why does the author point out that Mars has few ancient craters that are less than 5 kilometers in diameter?

A.To explain why scientists believe that the surface matter filling Martian craters is mostly dust.

B.To explain why scientists believe that the impact craters on Mars were created by meteoroids.

C.To support the claim that the Martian atmosphere is an efficient erosive agent.

D.To argue that Mars experienced fewer ancient impacts than the Moon did.

11.According to paragraph 5, what have scientists been able to determinefrom studies of large impact cratering on Mars?

A.Some Martian volcanoes are much older than was once thought.

B.The age of Mars’s surface can vary from area to area.

C.Large impact craters are not reliable indicators of age in areas with high volcanic activity.

D.Some areas of the Martian surface appear to be older than they actually are.

12.According to paragraph 6, the ejecta of Mars’s crater Yuty differs fromthe ejecta of the Moon’s Copernicus crater in that the ejecta of the Yuty crater

A.Has now become part of a permafrost layer.

B.Contains a large volume of dust, soil and boulders.

C.Suggests that liquid once came out of the surface at the crater site.

D.Was thrown a comparatively long distance from the center of the crater.

13. Look at the four squares【■】that indicate where the following sentence could be added to the passage.Where would the sentence best fit? Click on a square to add the sentence to the passage. This surface feature has led to speculation about what may lie under Mars’s surface.

The detailed appearance of Martian impact craters provides an important piece of information about conditions just below the planet’s surface. Martian craters are surrounded by ejecta (debris formed as a result of an impact) that looks quite different from its lunar counterparts. A comparison of the Copernicus crater on the Moon with the (fairly typical) crater Yuty on Mars demonstrates the differences. The ejecta surrounding the lunar crater is just what one would expect from an explosion ejecting a large volume of dust, soil, and boulders. ■【A】However, the ejecta on Mars gives the distinct impression of a liquid that has splashed or flowed out of crater. ■【B】Geologists think that this fluidized ejecta crater indicates that a layer of permafrost, or water ice, lies just a few meters under the surface. ■【C】Explosive impacts heated and liquefied the ice, resulting in the fluid appearance of the ejecta. ■【D】

14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.Drag your answer choices to the spaces where they belong. To remove an answer choice, click on it. To review the passage, click VIEW NEXT.

Volcanoes and impact craters are major features of Martiangeology.

A.Plate motion on Mars, once considered to have played no role in shaping the planet’s surface, is now seen as being directly associated with the planet’s earliest volcanoes.

B.Mars has shield volcanoes, some of which are extremely tall because of the planet’s low surface gravity.

C.Although the erosive power of the Martian atmosphere ensures that Mars has fewer craters than the Moon does, impact craters are prominent on Mars’ s surface.

D.Scientists cannot yet reliably estimate the age of the Martian surface because there has been too much erosion of it.

E.Scientists have been surprised to discover that conditions just below the surface of Mars are very similar to conditions just below the surface of the Moon

F.Studies of crater ejecta have revealed the possibility of a layer of permafrost below the surface of Mars.

托福阅读答案

1.enormous 巨大的，所以正确答案是B，extremely large。如果不认识，将答案代入原文， 原文说在T这个地方有三座非常大的火山，定语从句修饰说T是个什么样的地区，能容 下三座大火山的当然是很大的地方。A重要、C不寻常和D活跃都不靠谱。

2.注意问的是Olympus M，以这个词做关键词定位至第三句，讲O是最大的，所以正确答案只能是C，比较高，如果不确定可以往下看到最后一句，说三个大的跟O比起来要小点儿，也说明O比较大，其他答案都没说。

3.distinctive 有特点的，不同的，所以正确答案是 characteristic，dis作为前缀，有分或者 否定之意，所以猜出 distinctive 有不同的意思，这道词汇题代入原文不靠谱，因为几个错误答案带进去也说得通，大家还是抓紧背单词吧。

4.以A的 broad, sloping sides 做关键词定位至第二段第二句的破折号后，正确，不选;B选项的 smaller 定位至第一段尾句，正确，不选;C的channel 定位至第二段第三句，正确，不选;D 的数字定位至第一段倒数第二句，但25说的是O，而不是shield volcano， 所以D错，是答案。

5.roughly大概，所以正确答案是D的 approximately，代入原文，说火星的 gravity 只有地球的 40%，因此火星上山的高度应该大致是地球的 2.5倍，其他代入都说不通。

6.以Maxwell为关键词定位至第三段第四句，这句只是在比较，于是往前看，说gravity越低，高度越高，所以作者进行这个比较无外乎想证明这个结论，所以正确答案 A。C稍有迷惑性，但C的问题在于没有提及高度，只是单纯说不同 planet之间gravity的关系，错。

7.提出主干，没有证据，但是如果 blabla，有些火山至少 intermittently活跃，完全重复这 个意思的只有C，A 后半句的比较错，那句话事实上是条件;B同样因为比较排除;D强调的点与原文相反。

8.considerably相当地，显著地，程度大地，所以正确答案是 significantly，consider 做考 虑讲大家都知道，也就是说这个词至少应该被译为值得考虑的，所以可以得出B， frequently 说不通;clearly 只表示清楚，没法表示程度;surprisingly 带有主观色彩，同样不沾边。

9.以craters fill in much faster on Mars than on the Moon 定位至最后一句，说Martian atmosphere是erosive 的，风搬运尘土并擦掉撞击留下的痕迹，所以正确答案是D。

10.跟9题是同一题，定位至倒数第二句后，发现整个句子是个例子，然后看前句，发现同样是个例子，然后看后一句，就是第9题的那句话就可以找到答案 C 。

11.细节题，studies of large impact cratering on Mars 定位至首句，说是age indicator，但遗憾的是，凭这句只能排除 C，所以这道题只能读完这段，还好不长，答案在第二句，说南部和火山地区的不一样，也就是B说的不同地方age不同。

12.以Yuty做关键词定位至三五两句，第五句说火星的是液体，所以正确答案是C，第四句说月亮的ejecta是dust，soil and boulders，但问题问的是火星，所以答案不是B。

13.本来应该找代词 this surface feature 的，但这个词太抽象，所以没法定位，放弃;而且 Mar's surface 也不好，只能用动词变来的名词 speculation 做过渡点，同义词是原文的 think，所以正确答案非B即C，从逻辑上讲，应该先有导致 speculation，再有 speculation 是什么，所以正确答案是B不是C。

14.Plate motion 选项没有原文与之对应，尽管第二段提及了 plate motion，但跟选项说的 根本不是 一回事儿，错; Mars has 选项对应原文第三段，正确 Although 选项对应第四段首尾句，正确 Scientists cannot 选项与原文第五段信息相反，错 Scientists have been 选项与原文最后一段信息相反，错 ;Studies 选项对应原文最后一段最后一部分，正确。

托福阅读译文

【1】火星表面展示了很多种地理特征，包括巨大的火山——太阳系中已知的最大火山——以及覆盖范围很广的陨石坑。在塔尔西斯隆起——火星赤道附近的广阔地质区域——发现了三座非常大的火山。位于塔尔西斯西北的奥林帕斯山是其中最大的一座火山：25千米高，测得其基部直径大约有700千米。位于塔尔西斯隆起的三座大火山则略矮，高度“仅”达18千米。

【2】这些火山都不是因火星表面的板块碰撞而形成的——火星上并无板块运动。这些火山其实是盾状火山——一种由熔岩形成的斜面宽阔并且坡度平缓的火山。上述4座火山都具有非常明显的熔岩隧道以及其他流动特征，这与地球上的盾状火山相似。火星表面的图像显示那里存在成百上千的火山。那些最大的火山中的大部分都与塔尔西斯隆起有关，但是很多稍小的火山都分布在北部平原地区。

【3】火星上火山的可观的高度是该行星(相对)较低的地表重力导致的直接结果。当熔岩流淌和蔓延以形成盾状火山时，这座火山的最终高度取决于这座新生的山承载自身重量的能力。重力越低，重量就越小，山的高度就越高。如金星上的麦克斯韦山与地球上的夏威夷盾状火山从它们各自的基部算起海拔高度相同(大约10千米高)就不是什么巧合——地球与金星的地表重力相当。火星表面重力只有地球的40%，因此火星上的火山高度大致是地球的2.5倍。火星上的盾状火山是否还处于活跃期?科学家们没有直接证据显示这些火山近期是否喷发过，或是否正处于喷发阶段，但是如果这些火山近期的活跃状态一如一千万年前那般(这一最近的爆发期是根据火山斜坡上陨石坑的范围估算出来的)，它们当中的几个也许至少仍然会保持间歇性的活跃。然而，两次爆发之间也许间隔数百万年之久。

【4】火星表面的另一个突出特征是陨石坑。水手计划中的宇宙飞船发现在火星表面布满来自太空的流星撞击表面形成的陨石坑，火星的两颗卫星也是如此。与我们的月球类似，那些较小的陨石坑经常被一些物质填满(主要是灰尘)，这表明火星是一个干燥的沙漠世界。然而，与月球相比，火星上的陨石坑被填满的速度明显要快很多。在月球上，那些直径不足100米(对应深度大约在20米)的古老陨石坑主要因流星冲击而形成的尘埃的缘故而被填平了。而在火星上，只有相当少的一部分陨石坑直径小于5千米。火星大气是一种强效的腐蚀剂，加之火星上的风把灰尘从一个地方卷到另一个地方，较之仅仅是因流星冲击而形成的尘埃的作用，(火星上的)地表特征被消除得更快。

【5】与在我们的月球上相同，那些巨大陨石坑的范围(例如，那些巨大到自形成后尚未被尘埃填满的陨石坑)充当着火星表面年龄指示器的角色。从火星南部高地的40亿年至最年轻的火山地区的几千万年都是用同样的方法估算的。

【6】火星表面陨石坑的具体外貌为揭示该行星表面状况提供了非常重要的信息。火星陨石坑周边布满了喷出物(因撞击而形成的碎片)，这与月球上的陨石坑看起来非常不同。对比月球上的哥白尼陨石坑与火星上(相当典型的)尤蒂陨石坑可以看出不同。月球上陨石坑周边的喷出物正如我们以为的那样，一场爆炸喷出的大量的灰尘、土壤和岩石。然而，火星(上的陨石坑周边的)喷出物则因飞溅而出或溢出的液体给人留下了深刻的印象。地质学家认为这种具有流体化喷出物的陨石坑指示了在火星地表下几米处存在永冻土层或水冰。爆炸性的撞击加热并液化了这些冰，结果导致这些喷出物呈现流体状的特征。

托福阅读TPO25(试题+答案+译文)第1篇:The surface of Mars

篇4：托福阅读TPO7(试题+答案+译文)第:TheGeologicHistoryoftheMediterranean

托福阅读原文

In 1970 geologists Kenneth J.Hsu and William B.F. Ryan were collecting research data while aboard the oceanographicresearch vessel Glomar Challenger.Anobjective of this particular cruise wasto investigate the floor of theMediterranean and to resolve questions aboutits geologic history. One questionwas related to evidence that theinvertebrate fauna (animals without spines) ofthe Mediterranean had changedabruptly about 6 million years ago. Most of theolder organisms were nearlywiped out, although a few hardy species survived. Afew managed to migrate into the Atlantic.Somewhat later, the migrants returned,bringing new species with them. Why didthe near extinction and migrationsoccur?

Another task for the GlomarChallenger’sscientists was to try to determine the origin of the domelikemasses buried deepbeneath the Mediterranean seafloor. These structures had beendetected yearsearlier by echo-sounding instruments, but they had never beenpenetrated in thecourse of drilling. Were they salt domes such as are commonalong the UnitedStates Gulf Coast, and if so, why should there have been somuch solidcrystalline salt beneath the floor of the Mediterranean?

With question such as these clearly beforethem, thescientists aboard the Glomar Challenger processed to the Mediterraneantosearch for the answers. On August 23, 1970, they recovered a sample. Thesampleconsisted of pebbles of hardened sediment that had once been soft,deep-seamud, as well as granules of gypsum and fragments of volcanic rock. Nota singlepebble was found that might have indicated that the pebbles came fromthenearby continent. In the days following, samples of solid gypsumwererepeatedly brought on deck as drilling operations penetrated theseafloor.Furthermore, the gypsum was found to possess peculiarities ofcomposition andstructure that suggested it had formed on desert flats. Sedimentabove andbelow the gypsum layer contained tiny marine fossils, indicatingopen-oceanconditions. As they drilled into the central and deepest part oftheMediterranean basin, the scientists took solid, shiny, crystalline saltfromthe core barrel. Interbedded with the salt were thin layers of whatappeared tobe windblown silt.

The time had come to formulate ahypothesis. The investigators theorized that about 20 million years ago, theMediterranean wasa broad seaway linked to the Atlantic by two narrow straits.Crustal movements closedthe straits, and the landlocked Mediterranean began toevaporate. Increasingsalinity caused by the evaporation resulted in theextermination of scores ofinvertebrate species. Only a few organisms especiallytolerant of very saltyconditions remained. As evaporation continued, the remainingbrine (salt water)became so dense that the calcium sulfate of the hard layerwas precipitated. Inthe central deeper part of the basin, the last of the brineevaporated toprecipitate more soluble sodium chloride (salt). Later, under theweight ofoverlying sediments, this salt flowed plastically upward to form saltdomes.Before this happened, however, the Mediterranean was a vast desert 3,000metersdeep. Then, about 5.5 million years ago came the deluge. As a result ofcrustaladjustments and faulting, the Strait of Gibraltar, where theMediterranean nowconnects to the Atlantic, opened, and water cascadedspectacularly back intothe Mediterranean.Turbulent waters tore into thehardened salt flats, brokethem up, and ground them into the pebbles observed inthe first sample taken bythe Challenger. As the basin was refilled, normalmarine organisms returned.Soon layer of oceanic ooze began to accumulate abovethe old hard layer.

Thesalt and gypsum, the faunal changes, and the unusualgravel provided abundantevidence that the Mediterranean was once a desert.

托福阅读试题

1.The word “objective”in the passage(paragraph 1) is closest in meaning to

A.achievement

B.requirement

C.purpose

D.feature

2.Which of the following is NOT mentionedin paragraph 1 as a change thatoccurred in the fauna of the Mediterranean?

A.Most invertebrate species disappearedduring a wave of extinctions.

B.A few hardy species wiped out many of theMediterranean’s invertebrates.

C.Some invertebrates migrated to AtlanticOcean.

D.New species of fauna populated theMediterranean when the old migrants returned.

3.1.Whatdoes the author imply by saying“Not a single pebble was found that might have indicated that the

pebbles came from the nearby continent”?(paragraph 3)

A.The most obvious explanation for theorigin of the pebbles was not supported by the evidence.

B.The geologists did not find as manypebbles as they expected.

C.The geologists were looking for aparticular kind of pebble.

D.The different pebbles could not have comefrom only one source.

4.Which of the following can be inferredfrom paragraph 3 about the solidgypsum layer?

A.It did not contain any marine fossil.

B.It had formed in open-ocean conditions.

C.It had once been soft, deep-sea mud.

D.It contained sediment from nearbydeserts.

5.Select the TWO answer choice from paragraph3 that identify materialsdiscovered in the deepest part of the Mediterraneanbasin. To receive credityou must select TWO answers.

A.Volcanic rock fragments

B.Thin silt layers

C.Soft, deep-sea mud

D.Crystalline salt

6.What is the main purpose of paragraph 3?

A.To describe the physical evidencecollected by Hsu and Ryan

B.To explain why some of the questionsposed earlier in the passage could not be answered by the findings of theGlomar Challenger

C.To evaluate techniques used by Hsu andRyan to explore the sea floor

D.To describe the most difficult problemsfaced by the Glomar Challenger expedition

7.According to paragraph 4, which of thefollowing was responsible for theevaporation of the Mediterranean’s waters?

A.The movements of Earth’s crust

B.The accumulation of sediment layers

C.Changes in the water level of theAtlantic Ocean

D.Changes in Earth’s temperature

8.The word “scores”in the passage(paragraph 4) is closest in meaning to

A.members

B.large numbers

C.populations

D.different types

9.According to paragraph 4, what causedmost invertebrate species in theMediterranean to become extinct?

A.The evaporation of chemicals necessaryfor their survival

B.Crustal movements that connected theMediterranean to the saltier Atlantic

C.The migration of new species through thenarrow straits

D.Their inability to tolerate theincreasing salt content of the Mediterranean

10.Which of the sentences below bestexpresses the essential information inthe highlighted sentence in the passage(paragraph 4) ? Incorrect choices change the meaning inimportant ways or leaveout essential information.

A.The strait of Gibraltar reopened when theMediterranean and the Atlantic became connected and the cascades of water fromone sea to the other caused crustal adjustments and faulting.

B.The Mediterranean was dramaticallyrefilled by water from the Atlantic when crustal adjustments and faultingopened the Strait of Gibraltar, the place where the two seas are joined.

C.The cascades of water from the Atlanticto the Mediterranean were not as spectacular as the crustal adjustments andfaulting that occurred when the Strait of Gibraltar was connected to thoseseas.

D.As a result of crustal adjustments andfaulting and the creation of the Strait of Gibraltar, the Atlantic andMediterranean were connected and became a single sea with spectacular cascadesof water between them.

11.The word “Turbulent”in the passage(paragraph 4) is closest in meaning to

A.Fresh

B.Deep

C.Violent

D.Temperate

12. Look at the four squares [■] thatindicate where the following sentence could be added to the passage. Thus,scientists had information about the shape of the domes but not about theirchemical composition and origin.

■【A】Another task for theGlomar Challenger’s scientists was totry to determine the origin of thedomelike masses buried deep beneath theMediterranean seafloor. ■【B】These structures had been detected years earlierby echo-soundinginstruments, but they had never been penetrated in the courseof drilling. ■【C】Were theysalt domes such as are common alongthe United States Gulf Coast, and if so, whyshould there have been so muchsolid crystalline salt beneath the floor of theMediterranean? ■[D】

Where would the sentence best fit?

13. Direction: An introductory sentence fora brief summary of the passage is provided below. Complete the summary byselecting the THREE answer choices that express the most important ideas in thepassage. Some sentences do not belong in the summary because they express ideasthat are not presented in the passage or are minor ideas in the passage. Thisquestion is worth 2 points.

An expedition to the Mediterranean answeredsome long-standing questionsabout the ocean’s history.

A.The Glomar Challenger expeditioninvestigated changes in invertebrate fauna and some unusual geologic features.

B.Researchers collected fossils todetermine which new species migrated from the Atlantic with older species.

C.Scientists aboard the Glomar Challengerwere the first to discover the existence of domelike masses underneath theseafloor.

D.Samples recovered from the expeditionrevealed important differences in chemical composition and fossil distributionamong the sediment layers.

E.Evidence collected by the GlomarChallenger supports geologists' beliefs that the Mediterranean had evaporatedand become a desert, before it refilled with water.

F.Mediterraneansalt domes formed after crustal movements opened the straits between theMediterranean and the Atlantic, and the Mediterranean refilled with water.

托福阅读答案

1.C

2.文第四句话说到“Most of theolder organisms were nearly wiped out(大部分更加古老的生物都几乎灭绝了)”对应选项A;第五句说到“A few managed to migrate into the Atlantic(一些物种成功地迁移到了大西洋)”，对应选项C;第六句说到“the migrants returned, bringing new species with them(这些物种又回到了地中海，并带回新的物种)”，对应选项D。第一段中没有提到B 选项，故答案是B选项。

3.推理题考察的是文中没有明确说到的内容，需要经过推理。选项B、C、D在文中均没有任何线索体现。对于选项A，如果我们在阅读文章时，能够比较好的关注上下文，我们会发现：在原文之中第二段，文中提及“它们是像美国海湾海岸一带的含盐圆顶状巨块“ ---美国海湾的东西怎么会突然出现在了地中海区域?于是对于这些地中海的大巨块，最简单的解释是他们来自美洲湾。既然第二段提出了问题，第三段做出相应的回答，因此第三段的内容应该与第二段的问题是有联系的，支持或者反对。而现在的这句话(“在被发现的样品中，没有一个表明这些细砾来自于邻近的大陆”)，当然打破了这个最为明显的可能解释---关于巨大的块儿起源的解释。

4.A

5.BD

6.A

7.A

8.原文该单词所在句子为:”Increasingsalinity caused by the evaporation resulted in the extermination of scores ofinvertebrate species.“ 可以理解为: ”由蒸发引起的越来越高的盐度造成无脊椎动物种类的灭绝。“

Score是得分的意思，在球类比赛中经常可以听到，可以根据the extermination of scores of invertebrate species这个结构判断出scores表示数量的意思，对应选项B(这个还是记住吧)

9.D

10.B

11.C

12.C

13.选项A是正确的，是第一二段的内容

选项B是错误的，是文章未提及的内容

选项C是错位的，与第二段第二句内容相反

选项D是正确的，是第四段的内容

选项E是正确的，是文章最后一段的内容

选项F是错误的，与第四段内容不符，是地壳运动和断层作用打开了地中海和大西洋之间的海峡，并非盐穹(应该说domes在此之前就形成了)

托福阅读原文

【1】1970年，地理学家Kenneth J. Hsu 和 William B.F. Ryan在海洋调查船Glomar Challenger号上收集调研资料。这次特别巡航的一个目的是调查地中海的地层以及解决关于其地质历史的问题。其中一个问题是有关地中海地区无脊椎动物(没有脊椎的动物)于600万年前发生剧变的证据。大部分更加古老的生物都几乎灭绝了，尽管一些顽强的种类得以生存。很少的一些动物成功地迁移到了大西洋。不久后，这些动物又回来了，并带回来新的物种。为什么这次较近的动物灭绝和迁移会发生呢?

【2】Glomar Challenger号上科学家们的另一个任务是尝试去确定深埋在地中海海底穹顶状巨块的起源。这些结构在早些年被回声探测器探测过，但是它们从未被钻探过。它们是像美国墨西哥海湾海岸一带的含盐穹顶状巨块吗?如果是的话，为什么在地中海海底之下会有这么多固体的结晶盐呢?

【3】带着这些清楚摆在他们面前的问题，科学家们登上Glomar Challenger号前往地中海寻找答案。1970年8月23日，他们找到了一个样本。这个样本由石膏块和火山岩碎块组成。周围没有发现一块能说明这些小石头来自附近的大陆。接下来的日子里，随着海底岩层钻探实验的进行，固体石膏样本被不断地放在甲板上。而且，这些膏状物的组成和结构特性表明它们形成于沙漠。在石膏层上下的沉积物中包含了微小的海洋生物化石，说明了这是开放性的海洋环境。当钻到地中海盆地中心的最深处时，科学家们从钻管中获得了坚实的、光亮的结晶盐。跟结晶盐嵌在一起的薄层像是被风吹起的泥沙层。

【4】时间阐明了一个假设。调查者们构思了这样的理论：大约2 000万年前，地中海是一条宽阔的航道，它通过两条狭窄的海峡与大西洋连接。地壳运动封闭了海峡，被陆地包围的地中海也开始蒸发。由蒸发引起的越来越高的盐度造成无脊椎动物种类的灭绝。只有一些能抵抗高盐度条件的物种保留下来。随着蒸发的继续进行，盐水浓度太高以致硬地层的硫酸钙发生沉淀。在盆地的中间深处，剩余盐水的持续蒸发形成更多的可溶的氯化钠(盐)。后来，在上层沉淀物的重压下，盐向上形成了含盐的圆顶。然而在这之前，地中海是一个3 000米深的大沙漠。然后，550万年前发生了洪水。作为地壳调整和断层作用的结果，现在连接地中海和大西洋的直布罗陀海峡打开了，水流像瀑布一样壮观地涌回地中海。湍急的水流冲击并摧毁了坚硬的含盐层，把它们磨成了Challenger号获得的第一份样本中人们所观察到的鹅卵石。随着盆地的填充，普通的海洋生物又回来了。不久后海洋软泥层开始在原先的硬地层上堆积。

【5】盐、石膏、动物区系的变更，还有不寻常的沙砾层都为地中海曾经是片沙漠的理论提供了充分的证据。

托福阅读TPO7(试题+答案+译文)第1篇:The Geologic History of the Mediterranean

篇5：托福阅读TPO30(试题+答案+译文)第:ThePaceofEvolutionaryChange

托福阅读原文

【1】A heated debate has enlivened recent studies of evolution. Darwin's original thesis, and the viewpoint supported by evolutionary gradualists, is that species change continuously but slowly and in small increments. Such changes are all but invisible over the short time scale of modern observations, and, it is argued, they are usually obscured by innumerable gaps in the imperfect fossil record. Gradualism, with its stress on the slow pace of change, is a comforting position, repeated over and over again in generations of textbooks. By the early twentieth century, the question about the rate of evolution had been answered in favor of gradualism to most biologists' satisfaction.

【2】Sometimes a closed question must be reopened as new evidence or new arguments based on old evidence come to light. In 1972 paleontologist Stephen Jay Gould and Niles Eldredge challenged conventional wisdom with an opposing viewpoint, the punctuated equilibrium hypothesis, which posits that species give rise to new species in relatively sudden bursts, without a lengthy transition period. These episodes of rapid evolution are separated by relatively long static spans during which a species may hardly change at all.

【3】The punctuated equilibrium hypothesis attempts to explain a curious feature of the fossil record—one that has been familiar to paleontologist for more than a century but has usually been ignored. Many species appear to remain unchanged in the fossil record for millions of years—a situation that seems to be at odds with Darwin's model of continuous change. Intermediated fossil forms, predicted by gradualism, are typically lacking. In most localities a given species of clam or coral persists essentially unchanged throughout a thick formation of rock, only to be replaced suddenly by a new and different species.

【4】The evolution of North American horse, which was once presented as a classic textbook example of gradual evolution, is now providing equally compelling evidence for punctuated equilibrium. A convincing 50-million-year sequence of modern horse ancestors—each slightly larger, with more complex teeth, a longer face, and a more prominent central toe—seemed to provide strong support for Darwin's contention that species evolve gradually. But close examination of those fossil deposits now reveals a somewhat different story. Horses evolved in discrete steps, each of which persisted almost unchanged for millions of years and was eventually replaced by a distinctive newer model. The four-toed Eohippus preceded the three-toed Miohippus, for example, but North American fossil evidence suggests a jerky, uneven transition between the two. If evolution had been a continuous, gradual process, one might expect that almost every fossil specimen would be slightly different from every year.

【5】If it seems difficult to conceive how major changes could occur rapidly, consider this: an alteration of a single gene in files is enough to turn a normal fly with a single pair of wings into one that has two pairs of wings.

【6】The question about the rate of evolution must now be turned around: does evolution ever proceed gradually, or does it always occur in short bursts? Detailed field studies of thick rock formations containing fossils provide the best potential tests of the competing theories.

【7】Occasionally, a sequence of fossil-rich layers of rock permits a comprehensive look at one type of organism over a long period of time. For example, Peter Sheldon's studies of trilobites, a now extinct marine animal with a segmented body, offer a detailed glimpse into three million years of evolution in one marine environment. In that study, each of eight different trilobite species was observed to undergo a gradual change in the number of segments—typically an increase of one or two segments over the whole time interval. No significant discontinuous were observed, leading Sheldon to conclude that environmental conditions were quite stable during the period he examined.

【8】Similar exhaustive studies are required for many different kinds of organisms from many different periods. Most researchers expect to find that both modes of transition from one species to another are at work in evolution. Slow, continuous change may be the norm during periods of environmental stability, while rapid evolution of new species occurs during periods of environment stress. But a lot more studies like Sheldon's are needed before we can say for sure.

托福阅读试题

1.The word ”innumerable“ in the passage is closest in the meaning to

A.countless.

B.occasional.

C.large.

D.repeated.

2.According to paragraph 1, all of the following are true EXCEPT

A.Darwin saw evolutionary change as happening slowly and gradually.

B.Gaps in the fossil record were used to explain why it is difficult to see continuous small changes in the evolution of species.

C.Darwin's evolutionary thesis was rejected because small changes could not be observed in the evolutionary record.

D.By the early twentieth century, most biologists believed that gradualism explained evolutionary change.

3.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage paragraph 2 ? Incorrect choices change the meaning in important ways or leave out essential information.

A.The punctuated equilibrium hypothesis challenged gradualism, which holds that species evolve in relatively sudden bursts of brief duration.

B.The punctuated equilibrium hypothesis developed by Stephen Jay Gould and Niles Eldredge was challenged in 1972.C.In 1972 Stephen Jay Gould and Niles Eldredge challenged gradualism by positing that change from one species to another cannot occur without a lengthy transition period.

D.The punctuate equilibrium hypothesis, in opposition to gradualism, holds that transitions from one species to another occur in comparatively sudden burst.

4.According to paragraph 1 and paragraph 2, the punctuated equilibrium hypothesis and the gradualism hypothesis differed about

A.Whether the fossil record is complete.

B.Whether all species undergo change.

C.Whether evolution proceeds an a constant rate.

D.How many new species occur over long periods of time.

5.According to paragraph 3, the lack of intermediate fossils in the fossil record of some species

A.has been extensively studied by paleontologist for over a century.

B.contradicts the idea that most species have remained unchanged for millions of years.

C.challenges the view that evolutionary change is gradual.

D.is most common in the fossil records of clam and coral species.

6.The word ”compelling“ in the passage paragraph 4 is closest in the meaning to

A.surprising.

B.persuasive.

C.controversial.

D.detailed.

7.Paragraph 4 mentions that North American horses have changed in all the following ways EXCEPT in

A.the number of toes they have.

B.the length of their face.

C.their overall size.

D.the number of years they live.

8.The word ”alteration“ in the passage paragraph 5 is closest in meaning to

A.imperfection.

B.replacement.

C.change.

D.duplication.

9.According to paragraph 7, Peter Sheldon's studies demonstrated which ofthe following about trilobites?

A.They underwent gradual change over a long time period.

B.They experienced a number of discontinuous transitions during their history.

C.They remained unchanged during a long period of environmental stability.

D.They evolved in ways that cannot be counted for by either of the two competing theories.

10.The word ”occasionally“ in the passage paragraph 7 is closest in meaning to

A.undoubtedly.

B.basically.

C.once in a while.

D.to some extent.

11.The main purpose of paragraph 7 is to

A.Describe one test of the competing theories.

B.Provide an example of punctuated equilibrium.

C.Describe how segmented animals evidence both competing theories.

D.Explain why trilobites became extinct.

12. Look at the four squares [■] that indicate where the following sentence can be added to the passage.Where could the sentence best fit? They believe that environmental conditions may play a crucial role in determining which of the two modes will be in operation over a given period.

■【A】Similar exhaustive studies are required for many different kinds of organisms from many different periods. ■【B】Most researchers expect to find that both modes of transition from one species to another are at work in evolution.■【C】Slow, continuous change may be the norm during periods of environmental stability, while rapid evolution of new species occurs during periods of environment stress. ■【D】But a lot more studies like Sheldon's are needed before we can say for sure.

13.Directions: selected from the seven phrases below the phrases that correctly characterize punctuated equilibrium and the phrases that correctly characterize gradualism. Two of the phrases will not be used. This question is worth 3 points.

A.States that new species emerge from existing species during relatively brief period of time.

B.Was first formulated by Charles Darwin.

C.Explain why North American horses have become smaller over time.

D.States that new species evolve slowly and continuously from existing species.

E.Explain the lack of intermediate fossil forms in the fossil record of many species.

F.Competition is usually strongest when the density of the competing populations is the same.

G.States that a species will not change unless its environment changes.

1 )

Gradualism

A B C D E F G

2 )

punctuated equilibrium

A B C D E F G

托福阅读答案

1.innumerable是不可计数的，A是无数的，B是偶然的，C是大的，D是重复的。这个单词是numerable加否定前缀，很容易就能推出意思来。

2.A答案对应第一段第二句， B对应第一段第三句，D对应一段最后一句。C与原文冲突，原文一直在说darwin理论被人们广泛接受。

3.高亮句子的主干部分是断点平衡论挑战了原来的渐进论，然后解释了断点平衡论的内容。A选项which修饰不明，容易产生误解;B选项与原文矛盾，C与原文不符，原文S和N的观点是change的发生是without lengthy transition的。D和原文意思相符，并且也包含了所有的主干部分。

4.根据原文，渐进论是说物种演变是通过长时间的缓慢改变发生的;断点平衡论是说物种演变是短期爆发的。所以选择C，进化是否是匀速发生的。

5.根据lack of intermediate fossils定位到第三段倒数第二句，在往前看一句说，这一情况对于达尔文学说是不和的，而达尔文学说正是渐进论，这一段的最后也说原来的物种突然被替换，而不是渐渐进化改变的。所以C符合原文意思。 A与原文第一句破折号后矛盾，原文说这一现象一直被Ignored，B选项原文矛盾，该现象应该是反对了达尔文学说，支持了物种有长期不改变的论点。D虽然正确但是只是本段的细节，不能表达主题，所以不选。

6.Compel本身是强迫，此处作为evidence的形容词可以延伸为说服力强的。因此答案选B 有说服力的。A是惊奇的，C是有争议的，D是细节的。都不沾边。另外通过句义可以判断，前文说马的进化was once 是经典的渐进论的证明，is now(轻微转折)提了”equally“怎么样的证据证明了点断平衡论，前文既然说对gradual evolution很支持，那么后文出现equally，那应该对点断论也是有力证据。因此选B。

7.对应部分在第四段的第二句和第五句，只有D选项没有出现。

8.这一句话说一个怎么样的单一基因就足以变一个普通飞禽的一对的正常翅为两对翅膀，所以有推理应该是要改变这个基因。所以选C，Alteration是修改，变更，A选项是不完美，B是替换，D是复制 带入后都改变了原文的意思。

9.根据Peter Sheldon定位到原文第二句。后面对trilobites进行了描述，A选项对应了原文第三句，后文又继续说没有明显的断点。所以A正确。 B与原文第四句冲突。C与第三句冲突，D原文没有这种说法。而且上文也表明它符合gradual evolvement。

10.occasionally，是偶然偶尔的意思。A是毫无疑问的，B是基本上，C是偶尔有一次。D是在一定程度上。因此应该选C。并且上文提出问题说是否有过逐渐进化?那么下文给的是一个逐渐进化的例子，所以应该是在表达偶尔有一两个的意思。

11.上文说实地勘测会给competing theories提供test，第七段就给了试验例子，那么就证明是A正确。B与原文冲突，这个例子是支持渐进论的。C也不对，理由同上。D与原文目的不符。

12.首先句子开头出现了They，那么我们应该能在前文找到一个提到人物的地方，句子又提出environmental condition的作用，那么后文应该会出现对这一理论的解释，那么C是符合的，也可以进行代入验证。

13.A断点平衡论论点为物种变化发生突然，快速，符合。B对应文章第一段第一句话，符合渐进论。C与原文第四段第二句矛盾，原文说马进化会变大。不选。D原文第一段第一句，符合渐进论。E对应原文第三段。符合点断平衡论。F原文没提到，不选。G原文最后一段，说渐进论应该会是环境比较稳定的情况下的进化规则。符合渐进论。

托福阅读译文

【1】最近的一个关于进化的研究引发了激烈的争论。达尔文的原始论点和进化渐进主义者支持的观点是物种会持续地改变，但非常缓慢，增量也很小。这种改变是普遍的，但是现在短时间的观察是不能察觉的，并且，这个观点声称，它们通常被掩盖于不完美的化石记录的不可计数的缺失中。渐进主义及其对物种缓慢变化的引力让人欣然接受，并在世代的教科书中重复出现。在20世纪早前之前，令大部分的生物学家满足于利用渐进主义来回答关于进化速率的问题。

【2】有时，已经有了结论的问题必须由在已有证据基础上出现的新的证据和新的论点使其重新展开讨论。在1972年，古生物学者Stephen Jay Gould和 Niles Eldredge用相反的论点挑战了世俗的结论，即断点平衡说，它假设了物种演变为新的物种是通过相对突然的爆发，并非通过长时间的过渡时期。迅速的进化期被时间相对更长的静态期分开，而在静态时期，物种是几乎完全不变的。

【3】断点平衡论试着去解释化石记录的一个古怪的特点----在超过一个世纪的时间里它已经为古生物学者所熟悉，但一直被忽视。许多物种似乎在上百万年的化石记录中一直没有改变，这个情况与达尔文的模型所支持的物种的持续变化相悖。进化渐进论的支持者所预测的中间状态的化石一直没有出现。在大部分蛤和珊瑚的聚集地，其化石在很厚的岩石中都实际上没有变化，只是突然被另一新的并且不同的物种而取代。

【4】北美马的进化曾经被用作经典的教科书案例来证明渐变进化论，现在却为断点平衡学提供了同样有说服力的证据。一个有说服力的5千万年的马祖先的进化模型----每一代都稍稍大一点，有更复杂的牙齿，更长的脸，和中间更突出的脚趾----这一切都看似强有力的支持了达尔文的论点，物种是逐步地进化的。但是，对这些化石更严谨的验证现在揭示了一个不太一样的故事。马是在不连续的步骤中进化的，其中每个进化步骤中间都有上百万年时间保持不变，在最后被一个不同的更新的模型取代。比如四只脚趾的Eohippus 在三只脚趾的moihippus之前，但北美化石证据表明在这之间有一个不平稳的，不均衡的转换过程。如果进化一直都是连续，渐进的过程，人们应该预期到的是每年的化石样本都会存在细微的差别。

【5】如果很难设想大的改变会迅速发生，想想这些：一个单一基因的改变就足以将有一对翅膀的苍蝇变成两对翅膀。

【6】关于进化速度的问题现在发生了转变：进化过程是逐渐发生的么，还是总是突然短时间的爆发?对含有化石的厚岩层的细致的现场调查可以检验这两个备受争论的理论。

【7】偶尔，有一个系列的化石丰富的岩石可以允许人们综合性的观察一种生物在很长一段时间中的变化。比如，Peter Sheldon对于三叶虫，一种已灭绝的身体分节的海洋生物，的研究提供了其对三百万年来在同一海洋环境下进化的一些细节。研究中，八种三叶虫都观察到了其身体节数数量逐渐改变的过程，在整个时间段中，一般身体都增加了一到两节。没有明显的不连贯，这使sheldon得出结论：海洋环境在那段时间是比较稳定的。

【8】很多来自不同时期的不同的生物都需要开展相似的相近研究。大多数研究者希望发现物种进化的这两种模式都存在。缓慢的，连续的变化可能是在环境稳定的时间段下的规律，而快速进化的新物种则发生在环境变化时期的压力下。但是，我们需要更多的想Sheldon所做的研究以证明这个观点。

托福阅读TPO30(试题+答案+译文)第2篇:The Pace of Evolutionary Change

篇6：托福阅读TPO28(试题+答案+译文)第:EarlySaharanPastoralists

托福阅读原文

【1】The Sahara is a highly diverse, albeit dry, region that has undergone major climatic changes since 10,000 B.C. As recently as 6,000 B.C. the southern frontier of the desert was far to the north of where it is now, while semiarid grassland and shallow freshwater lakes covered much of what are now arid plains. This was a landscape where antelope of all kinds abounded—along with Bos primigenius, a kind of oxen that has become extinct. The areas that are now desert were, like all arid regions, very susceptible to cycles of higher and lower levels of rainfall, resulting in major, sudden changes in distributions of plants and animals. The people who hunted the sparse desert animals responded to drought by managing the wild resources they hunted and gathered, especially wild oxen, which had to have regular water supplies to survive.

【2】Even before the drought, the Sahara was never well watered. Both humans and animals were constantly on the move, in search of food and reliable water supplies. Under these circumstances, archaeologist Andrew Smith believes, the small herds of Bos primigenius in the desert became smaller, more closely knit breeding units as the drought took hold. The beasts were more disciplined, so that it was easier for hunters to predict their habits, and capture animals at will. At the same time, both cattle and humans were more confined in their movements, staying much closer to permanent water supplies for long periods of time. As a result, cattle and humans came into close association.

【3】Smith believes that the hunters were well aware of the more disciplined ways in which their prey behaved. Instead of following the cattle on their annual migrations, the hunters began to prevent the herd from moving from one spot to another. At first, they controlled the movement of the herd while ensuring continuance of their meat diet. But soon they also gained genetic control of the animals, which led to rapid physical changes in the herd. South African farmers who maintain herds of wild eland (large African antelopes with short, twisted horns) report that the offspring soon diminish in size, unless wild bulls are introduced constantly from outside. The same effects of inbreeding may have occurred in controlled cattle populations, with some additional, and perhaps unrecognized, advantages. The newly domesticated animals behaved better, were easier to control, and may have enjoyed a higher birth rate, which in turn yielded greater milk supplies. We know from rock paintings deep in the Sahara that the herders were soon selecting breeding animals to produce offspring with different horn shapes and hide colors.

【4】It is still unclear whether domesticated cattle were tamed independently in northern Africa or introduced to the continent from southwest Asia. Whatever the source of the original tamed herds might have been, it seems entirely likely that much the same process of juxtaposition (living side by side) and control occurred in both southwest Asia and northern Africa, and even in Europe, among peoples who had an intimate knowledge of the behavior of wild cattle. The experiments with domestication probably occurred in many places, as people living in ever-drier environments cast around for more predictable food supplies.

【5】The cattle herders had only a few possessions: unsophisticated pots and polished adzes. They also hunted with bow and arrow. The Saharan people left a remarkable record of their lives painted on the walls of caves deep in the desert. Their artistic endeavors have been preserved in paintings of wild animals, cattle, goats, humans, and scenes of daily life that extend back perhaps to 5,000 B.C.. The widespread distribution of pastoral sites of this period suggests that the Saharans ranged their herds over widely separated summer and winter grazing grounds.

【6】About 3,500 B.C., climatic conditions again deteriorated. The Sahara slowly became drier and lakes vanished. On the other hand, rainfall increased in the interior of western Africa, and the northern limit of the tsetse fly, an insect fatal to cattle, moved south. So the herders shifted south, following the major river systems into savanna regions. By this time, the Saharan people were probably using domestic crops, experimenting with such summer rainfall crops as sorghum and millet as they move out of areas where they could grow wheat, barley, and other Mediterranean crops.

[Glossary]

adzes: cutting tools with blades set at right angles to the handle.

托福阅读试题

1.According to paragraph 1, what was true of the Sahara region around 6,000 B.C.?

A.Much less of it was desert than is now the case.

B.Most areas that are now grassland were covered by shallow lakes.

C.It had just undergone a major climatic change.

D.Wild oxen and antelopes lived in separate parts of the region.

2.The word ”albeit“ in the passage(paragraph 1)is closest in meaning to

A.usually.

B.almost.

C.though.

D.rather.

3.According to paragraph 1, which of the following is true of all arid regions?

A.They include at least some freshwater lakes.

B.They have similar distributions of plants and animals.

C.They are greatly affected by changes in the amount of rain they receive.

D.They have frequent droughts that make it difficult to manage the wild resources.

4.Paragraph 2 supports which of the following ideas about wild oxen in the Sahara region after the drought took hold?

A.They traveled in smaller herds.

B.They were harder for hunters to capture.

C.They tended to be significantly smaller in size.

D.They moved along less predictable routes.

5.According to paragraph 2, what was it that brought cattle and humans into close association?

A.The development of smaller breeding units within hers.

B.Cattle and humans staying close to permanent water supplies for long period of time.

C.The development of greater discipline among cattle.

D.Cattle and humans constangly on the move searching for food and reliable water supplies.

6.Why does the author mention the ”rock paintings deep in the Sahara“?

A.To help explain why the hunters wanted to control the herds.

B.To provide support for the idea that the herders soon gained genetic control of the cattle

C.To show that the herders had artistic as well as practical abilities

D.To argue that the herders soon began to value their cattle for more than food.

7.According to paragraph 3, all of the following statements were true of newly domesticated animals EXCEPT

A.They were controlled more easily by the farmers.

B.They produced a larger number of offspring.

C.They produce more milk.

D.They were larger in size.

8.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage paragraph 4 ? Incorrect choices change the meaning in important ways or leave out essential information.

A.Regardless of where the first tamed herds came from, people tried to control them by living in juxtaposition with them.

B.Regardless of where the first tamed herds came from, they resulted from the same process of juxtaposition and control by people who understood the behavior of wild cattle.

C.People who had an intimate knowledge of the behavior of wild cattle moved closer together to cooperate in taming the herd, regardless of where they found them.

D.The process of taming herds was certainly the same in southwest Asia, northern Africa, and Europe because people knew a lot about the behavior of wild cattle, regardless of where they lived.

9.According to paragraph 5, each of the following was true about the early Saharan people EXCEPT

A.They had few possessions apart from cattle.

B.After about 5,000 B.C., they lived primarily in caves that were located deep in the desert.

C.Between the summer and winter seasons, they moved their herds over long distances.

D.They painted animals and scenes of daily life on the walls of caves.

10.The word ”endeavors“ in the passage is closest in meaning to

A.methods.

B.styles.

C.scenes.

D.efforts.

11.The word ”deteriorated“ in the passage is closest in meaning to

A.became unstable.

B.caused hardship.

C.changed completely.

D.got worse.

12.According to paragraph 6, what allowed the herders to shift south into the savanna regions after about 3,500 B.C.?

A.They could easily grow Mediterranean crops in those regions.

B.They could more easily domesticated sorghum and millet in those regions.

C.The tsetse fly was no longer a problem in those regions.

D.The river systems in those regions provided reliable sources of water in the summer.

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage. Where would the sentence best fit? This knowledge enabled the hunters to adopt a different approach to hunting.

Smith believes that the hunters were well aware of the more disciplined ways in which their prey behaved. ■【A】Instead of following the cattle on their annual migrations, the hunters began to prevent the herd from moving from one spot to another. ■【B】At first, they controlled the movement of the herd whileensuring continuance of their meat diet. ■【C】But soon they also gained genetic control of the animals, which led to rapid physical changes in the herd. ■【D】South African farmers who maintain herds of wild eland (large African antelopes withshort, twisted horns) report that the offspring soon diminish in size, unless wild bulls are introduced constantly from outside. The same effects of inbreeding may have occurred in controlled cattle populations, with some additional, and perhaps unrecognized, advantages. The newly domesticated animals behaved better, were easier to control, and may have enjoyed a higher birth rate, which in turn yielded greater milk supplies. We know from rock paintings deepin the Sahara that the herders were soon selecting breeding animals to produce offspring with different horn shapes and hide colors.

14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

As recently as 6,000 B.C., much ofthe Sahara region was semiarid grassland where humans hunted wild oxen andantelope.

A.There was enough freshwater for Saharan peoples to move freely throughout the region without having to manage the resources they hunted and gathered.

B.Once Saharans controlled the breeding of their cattle, the characteristics of the cattle changed rapidly, increasing their reproductive rate and milk production.

C.Although the Saharan peoples were remarkably sophisticated artists, they had only a few simple possessions, like adzes and the bows and arrows they used for hunting.

D.When the drying climate forced cattle and humans close to each other in areas with water supplies, humans gained control over the cattle and eventually domesticated them.

E.Herders soon began selecting breeding animals to produce offspring with different horn shapes and hide colors, although the advantage of controlled inbreeding were not apparent to them at first.

F.As the drought worsened around 3,500 B.C. and conditions for herders became more favorable to the south, the Saharan people moved into savanna regions, where they grew different crops.

托福阅读答案

1.原文写到”在公元前六千年左右，在沙漠的南边界，远离北边的地方现在是干旱的平原，当时这里是各种羚羊和原始牛都很丰富的山水画般的地方“那么也就是说那时候那个地方还不是沙漠。所以A，当时沙漠要比现在少，正确。B现在没grassland。C并没说这个改变是在公元前60发生的。D通过”along with“可以知道这两种动物是生活在一起的。

2.通过原文albeit前后两个词可以推出转折意义，前面是多样性的，后面是干燥的，两者有褒贬对比，所以选C

3.根据all arid region定位(红色标出句)选项A错误，原文没说。B，原文虽然提到了distribution of plants，但是并没说所有的干燥地区这一点都是相似的。C正确，原文说very susceptible to higher and lower levels of rainfall。D错误，最后一句说人们因此而开始manage resources。

4.对应文章地三句，第四句。根据原文说这种牛群体更小了，繁殖的单位更小，别驯化了，跟容易被预测。所以B，D错误，C原文没提到，只说其群体变小。也就是A。

5.根据close association定位到最后一句，但这句说as a result，那么原因就在前面一句。前一句说cattle human都staying much closer to permanent water supplies。所以完美的对应了B。

6.这个例子之前一直在说herders gained genetic control和其影响。然后给出这个例子，后面的内容也在说放牧人是怎样进行基因控制的。所以应该选B。

7.根据domesticated animals 定位到这一段后半部分，已用红色字标出，加粗字体为domesticated animals的描述。D没提到。所以选D。

8.这里的主干内容是，不管驯化动物从哪起源的，最后在不同的地区得到的都是同样的方法：juxtaposition，control。根据以上信息对选项进行排除。

A：前半句没问题。后半句和原文关系不符

B：正确，包括了所有主干部分。

C：完全和原文说的不是一回事儿啊。

D：原文并没有因果关系。

9.A对应第一句，除了牛，他们还有住所和斧头。C对应最后一句。D对应第三句。B，原文虽然说到他们在沙漠深处的洞穴里画画了，但是没说他们住那。所以不对，选B。

10.Endeavor是努力，尽力的意思。A是方法;B风格;C景象;D努力。所以D最贴切。从文章可以推测。之前在描述他们的生活场景，财产，打猎。然后说他们画画。这里问的是记录了什么，那么应该是他们之前做出的努力。别的单词带入后都解释不通。

11.通过这个词后面的一句话对撒哈拉的描写可以看出都是负面发展。更干燥，湖也消失了。A是不稳定，B是困苦，C是完全改变。

12.根据move south和savanna region定位到原文字体标注处，这句话开头出现So，那证明往前一句就是原因。前一句说西部降水变多了，并且northern limit of the tsetse fly moved south，所以牛群也move south。对应了C选项。D可能是个迷惑选项，但是按原文的意思，river只是牛迁徙的路径”following“，但并不是原因。

13.需要插入的句子说”这个知识使得猎人改变了打猎的方法“。那么前面应该说猎人得到了什么知识，后面应该说这个方法怎么改变了。A选项完美符合了这个逻辑和内容。

提供者：请选择

14.A错误，原文说因为干旱，所以农民开始manage the resources。对应原文第一段最后一句。B错误，原文说因为干旱，所以农民开始manage the resources。对应原文第一段最后一句。C正确。对应原文第三段。D前半句正确，但后半句不对，在他们选中种畜之后，已经明确的知道了好处。E虽然这句内容文章都有提到，但是并没有although这样的逻辑变化。所以不选。F正确。对应文章最后一段。

托福阅读译文

【1】尽管干旱，撒哈拉的物种极其多样，并自公元前10,000年前开始已经历了数次重大气候变迁。直到公元前6,000年前，沙漠的南部边界比现在的位置要靠北很多，那时半干旱的草原和浅淡水湖泊覆盖了现在干旱的平原。这里曾经是各种羚羊和一种已灭绝的野牛出没的地方。现在的沙漠地区，像所有干旱地区一样，对降雨量的变化周期极为敏感，因而其动植物的分布变化巨大且迅速。依靠捕食稀少的沙漠动物的居民对待干旱的方式是管理他们捕捉和收集到的野生资源，尤其是需要可靠水源维持生命的野牛。

【2】甚至在干旱之前，撒哈拉地区也从未有充足的水分。人类和野生动物都不停的迁徙，以寻找食物和可靠的水源。在这些情况下，考古学家Andrew Smith 认为随着干旱的持续，沙漠中野牛群会变成更小，组织更紧密的族群。兽群变得更加自律，因此猎人更容易预测他们的习性并随意抓捕。同时，骆驼和人类的行动范围进一步靠近，在固定水源附近长期更亲近的共处。结果骆驼和人类形成了紧密的联合。

【3】Smith相信猎人对猎物更加自律的行为了然于胸。猎人们不再跟随骆驼进行每年一度的迁徙而是开始阻止兽群的迁移。起初他们控制兽群的迁移以获得持续的肉食来源。但很快他们能够在遗传上控制动物，使得兽群的体征迅速变化。南非牧养大羚羊(一种体型较大的非洲羚羊，它们的角短且扭曲)的农民说如果不持续从野外引进公羚羊则其后代体型迅速变小。近亲繁殖的影响同样发生在控制拥有某些额外的可能并未认清的优势的骆驼数量上。最新驯化的动物更易控制，出生率也更高，而反过来也会提供更多奶源。我们从撒哈拉腹地的岩石绘画可知牧民很快就选择一些动物进行繁殖以产生角和颜色不同的后代。

【4】我们仍无法知道骆驼是在北非独立驯化的还是从东南亚引入的。不管驯化的兽群起源何处，东南亚和北非，甚至是欧洲的那些对野生骆驼的行为了然于胸的人们都可能经过了同样的和他们要驯化的动物毗邻而居并逐渐控制它们的过程。随着人们居住环境不断干燥和食物供给的可预测性更强，驯化的尝试很可能发生在很多地方。

【5】骆驼牧养人的财产很少：一些并不精致的罐子和磨光的斧子。他们也利用弓箭捕猎。撒哈拉人在撒哈拉腹地洞穴的墙壁上留下了很重要的关于他们生活的记录。他们的艺术创作保存了大量关于野生动物、骆驼、山羊、人类及其日常生活的各种场景的绘画。这些场景可能追溯到公元前5,000年前。这一时期田园画古迹的广泛分布表明撒哈拉人曾在广泛且独立的牧场上放牧。

【6】大约公元前3,500年前，气候条件又一次恶化。撒哈拉沙漠渐渐地更加干旱，湖泊相继干涸。另外西非内陆降雨增加，并且舌蝇，一种对骆驼致命的昆虫，的种群的北部边界向南移动。所以骆驼牧民也追随大平原区域的主要河流系统向南迁徙。此时，随着撒哈拉人从原本可以种植小麦、大麦和其它一些地中海农作物的区域中迁出，他们可能依靠当地的农作物，例如像高粱和小米一类的依靠夏季降雨的作物。

托福阅读TPO28(试题+答案+译文)第2篇:Early Saharan Pastoralists

篇7：托福阅读TPO3(试题+答案+译文)第:TheLong-TermStabilityofEcosystems

托福阅读原文

Plant communities assemble themselvesflexibly, and their particular structure depends on the specific history of thearea. Ecologists use the term “succession” to refer to the changes that happenin plant communities and ecosystems over time. The first community in asuccession is called a pioneer community, while the long-lived community at theend of succession is called a climax community. Pioneer and successional plantcommunities are said to change over periods from 1 to 500 years. Thesechanges—in plant numbers and the mix of species—are cumulative. Climaxcommunities themselves change but over periods of time greater than about 500years.

An ecologist who studies a pond today maywell find it relatively unchanged in a year’s time. Individual fish may bereplaced, but the number of fish will tend to be the same from one year to thenext. We can say that the properties of an ecosystem are more stable than theindividual organisms that compose the ecosystem.

At one time, ecologists believed that speciesdiversity made ecosystems stable. They believed that the greater the diversitythe more stable the ecosystem. Support for this idea came from the observationthat long-lasting climax communities usually have more complex food webs andmore species diversity than pioneer communities. Ecologists concluded that theapparent stability of climax ecosystems depended on their complexity. To takean extreme example, farmlands dominated by a single crop are so unstable thatone year of bad weather or the invasion of a single pest can destroy the entirecrop. In contrast, a complex climax community, such as a temperate forest, willtolerate considerable damage from weather to pests.

The question of ecosystem stability iscomplicated, however. The first problem is that ecologists do not all agreewhat “stability” means. Stability can be defined as simply lack of change. Inthat case, the climax community would be considered the most stable, since, bydefinition, it changes the least over time. Alternatively, stability can bedefined as the speed with which an ecosystem returns to a particular formfollowing a major disturbance, such as a fire. This kind of stability is alsocalled resilience. In that case, climax communities would be the most fragileand the least stable, since they can require hundreds of years to return to theclimax state.

Even the kind of stability defined assimple lack of change is not always associated with maximum diversity. At leastin temperate zones, maximum diversity is often found in mid-successionalstages, not in the climax community. Once a redwood forest matures, forexample, the kinds of species and the number of individuals growing on theforest floor are reduced. In general, diversity, by itself, does not ensurestability. Mathematical models of ecosystems likewise suggest that diversitydoes not guarantee ecosystem stability—just the opposite, in fact. A morecomplicated system is, in general, more likely than a simple system to breakdown. A fifteen-speed racing bicycle is more likely to break down than achild’s tricycle.

Ecologists are especially interested toknow what factors contribute to the resilience of communities because climaxcommunities all over the world are being severely damaged or destroyed by humanactivities. The destruction caused by the volcanic explosion of Mount St.Helens, in the northwestern United States, for example, pales in comparison tothe destruction caused by humans. We need to know what aspects of a communityare most important to the community’s resistance to destruction, as well as itsrecovery.

Many ecologists now think that the relativelong-term stability of climax communities comes not from diversity but from the“patchiness” of the environment, an environment that varies from place to placesupports more kinds of organisms than an environment that is uniform. A localpopulation that goes extinct is quickly replaced by immigrants from an adjacentcommunity. Even if the new population is of a different species, it canapproximately fill the niche vacated by the extinct population and keep thefood web intact.

托福阅读试题

1. The word “particular” in the passage(paragraph 1) is closest in meaning to

A.natural

B.final

C.specific

D.complex

2. According to paragraph 1, which of thefollowing is NOT true of climax communities?

A.They occur at the end of a succession.

B.They last longer than any other type ofcommunity.

C.The numbers of plants in them and the mixof species do not change.

D.They remain stable for at least 500 yearsat a time.

3. According to paragraph 2, which of thefollowing principles of ecosystems can be learned bystudying a pond?

A.Ecosystem properties change more slowlythan individuals in the system.

B.The stability of an ecosystem tends tochange as individuals are replaced.

C.Individual organisms are stable from oneyear to the next.

D.A change in the members of an organismdoes not affect an ecosystem’s properties.

4. According to paragraph 3, ecologistsonce believed that which of the following illustratedthe most stableecosystems?

A.Pioneer communities

B.Climax communities

C.Single-crop farmlands

D.Successional plant communities

5. According to paragraph 4, why is thequestion of ecosystem stability complicated?

A.The reasons for ecosystem change are notalways clear.

B.Ecologists often confuse the word“stability” with the word “resilience.”

C.The exact meaning of the word “stability”is debated by ecologists.

D.There are many different answers toecological questions.

6. According to paragraph 4, which of thefollowing is true of climax communities?

A.They are more resilient than pioneercommunities.

B.They can be considered both the most andthe least stable communities.

C.They are stable because they recoverquickly after major disturbances.

D.They are the most resilient communitiesbecause they change the least over time.

7. Which of the following can be inferredfrom paragraph 5 about redwood forests?

A.They become less stable as they mature.

B.They support many species when they reachclimax.

C.They are found in temperate zones.

D.They have reduced diversity duringmid-successional stages.

8. The word “guarantee” in the passage(paragraph 5) is closest in meaning to

A.increase

B.ensure

C.favor

D.complicate

9. In paragraph 5, why does the authorprovide the information that “A fifteen-speed racing bicycle is more likely tobreak down than a child’s tricycle”?

A.To illustrate a general principle aboutthe stability of systems by using an everyday example

B.To demonstrate that an understanding ofstability in ecosystems can be applied to help understand stability in othersituations

C.To make a comparison that supports theclaim that, in general, stability increases with diversity

D.To provide an example that contradictsmathematical models of ecosystems

10. The word “pales” in the passage(paragraph 6) is closest in meaning to

A.increases proportionally

B.differs

C.loses significance

D.is common

11. Which of the sentences below bestexpresses the essential information in the highlighted sentence in the passage(paragraph 7)? Incurred choices change the meaning in important ways or leaveout essential information.

A.Ecologists now think that the stabilityof an environment is a result of diversity rather than patchiness.

B.Patchy environments that vary from placeto place do not often have high species diversity.

C.Uniform environments cannot be climaxcommunities because they do not support as many types of organisms as patchyenvironments.

D.A patchy environment is thought toincrease stability because it is able to support a wide variety of organisms.

12. The word “adjacent” in the passage(paragraph 7) is closest in meaning to

A.foreign

B.stable

C.fluid

D.neighboring

13. Look at the four squares [█] thatindicate where the following sentence could be added to the passage. In fact,damage to the environment by humans is often much more severe than damage bynatural events and processes.

█【A】Ecologists are especially interested to know what factors contributeto the resilience of communities because climax communities all over the worldare being severely damaged or destroyed by human activities. █【B】The destructioncaused by the volcanic explosion of Mount St. Helens, in the northwesternUnited States, for example, pales in comparison to the destruction caused byhumans. █【C】We need toknow what aspects of a community are most important to the community’sresistance to destruction, as well as its recovery. █【D】

Where would the sentence best fit? Click ona square to add the sentence to the passage.

14. Directions: Anintroductory sentence for a brief summary of the passage is provided below.Complete the summary by selecting the THREE answer choices that express themost important ideas in the passage. Some sentences do not belong in thesummary because they express ideas that are not presented in the passage or areminor ideas in the passage. This question is worth 2 points.

The process of succession and the stabilityof a climax community can change over time.

A.The changes that occur in an ecosystemfrom the pioneer to the climax community can be seen in one human generation.

B.A high degree of species diversity doesnot always result in a stable ecosystem.

C.The level of resilience in a plantcommunity contributes to its long-term stability.

D.Ecologists agree that climax communitiesare the most stable types of ecosystems.

E.Disagreements over the meaning of theterm “stability” make it difficult to identify the most stable ecosystems.

F.The resilience of climax communitiesmakes them resistant to destruction caused by humans.

托福阅读答案

1. particular特别的，特定的，答案specific。前文说assemblethem flexibly，多变的，就是每个群落都不一样，强调特殊性。A自然B最终D复杂都与前文不搭，所以都不对

2.以climax communities做关键词定位至原文第三句和最后一句，第三句说明A对，不选;最后一句说明D对，不选;B没直说，说其他的communities 变化周期在1-500年，climax最少是500年，说明climax最长，B对，不选。而且最后一句也说了climax是变化的，C说反了，选

3.本段非常短，迅速看完之后发现最后一句是结论，说生态系统比组成生态系统的任意单一物种都稳定，A是答案

4.以ecologists做关键词定位至本段第一句，说生态学家认为生态系统中物种越多越稳定。接着在举例子的时候作者举到了climax communities，说明生态学家认为climax communities最稳定，答案B

5.以question ofecosystem stability为关键词定位至本段头两句，说生态学家对于什么是生态系统的稳定性依然存在争议，C是原文的忠实改写

6.关于climax communities原文有两个地方提到。因为生态学家对什么是稳定这个问题存在两个观点，以不变这种观点看，climax是最稳定的，以快速恢复这种观点看，climax是最不稳定的，所以climax既稳定也不稳定，B明确说到两个方面，其它选项都只说到一个方面

7.以redwood forest做关键词定位至原文第三句，事实上这个redwood是前句的一个具体例子，前面句说至少在温带，mid是最稳定的，不是climax，紧接着就举了一个redwood的例子，可以推断redwood是温带植物，C是答案。A/B/D都与原文意思相反，而且B和D基本上意思一样，都不对

8.本句中有个likewise，说明它与前面句子构成类比，前句说diversity does not ensure stability, 后文的内容几乎和前句一模一样，除了动词被替换，因此guarantee的意思就是ensure

9.括号的作用是解释括号之前的文字，前文说系统越复杂越容易坏，后面举了十五速赛车和小孩子的三轮车的例子，三轮车明显比赛车简单，所以就是支持前文，A正确，C正好说反，其他都没说

10.pale苍白，使什么什么苍白之意。单词所在句之前说很多climax communities都被人类破坏了，也就是强调人的破话很严重。后面举了个例子，说圣海伦斯火山爆发造船的破坏还没有人类活动的破坏严重，所以C选项lose significance正确

11.原文的结构是生态系统的长期稳定性不是因为blablabla，而是因为blablabla，又对这个进行了解释，说物种多;A说反;B错，因为原文没有说patchiness和diversity是矛盾的;C错，因为原文比较的是patchiness和uniform，而C直接将patchiness和clima_行比较，偷换概念;D正确，注意原文貌似没有明显的因果关系，因此可能单看句子间关系的话会排除D，但原文后半句整个是对patchiness的一种解释，所以存在不明显的因果关系

12.adjacent是相邻之意，原文说本地的population灭绝的话会被哪里来的群落补充，可能的只有foreign和neighboring，这两个选项代入原文都是可以的，除知道这个单词的意思之外，还可以认为相邻的群落更有可能迅速补充，而外来的范围太大，不对

13.根据待插入句中的human判断，A/B/C是可能的，naturalevents and processes自然的过程，与第二句中的圣海伦斯火山爆发是同义替换，所以B/C可能正确，但按照先理论后实例的原则，正确答案是B不是C

14.Thechanges选项与原文首段的最后一句意思相反，不选

A high degree选项对应原文第三段和第五段的首句，第四段的最后一句，正确

The level选项对应原文第六段首句，第四段倒数第二第三句，正确

Ecologists选项与原文第三段第四段的首句意思相反，不选

Disagreements选项对应原文第四段第二句，正确

The resilience选项原文没说，原文第六段说不知道为什么生物群落能抵抗破坏，不选

托福阅读译文

植物群体可以自由地聚集，它们特殊的结构取决于聚集区域的具体历史。生态学家使用“演替”来诠释植物群落和生态系统随着时间推移所发生的变化。演替中的第一个群落被称作先锋群落，而处于演替最后那个长期生存的群落被称为顶极群落。先锋群落和紧接着的植物群落的变化周期是从1到500年不等，植物数量和混合种类数量的变化是慢慢积累的。顶极群落本身也改变，但其变化周期超过500 年。

现代一个研究池塘的生态学会发现池塘在一年当中相对而言是不变的。个别鱼类可能被替换，但年复一年鱼的总数都趋于一致。也就是说，一个生态系统自身的属性要比由单一生物体组成的生态系统更稳定。

生态学家们一度认为物种的多样性使生态系统稳定，生态系统物种越多样则生态系统越稳定。通过观察得出的结论支持了这个观点，长期持久的顶极群落通常要比先锋群落具备更为复杂的食物网和更多的物种。生态学家家们得出的结论是：顶点生态系统的稳定性明显取决于他们的复杂化程度。举个极端的例子，在单一作物的农田中，一年的恶劣天气或单一害虫的入侵就可以摧毁所有作物。与此相反，在一个复杂的顶极群落里，如温带森林，他们便可以抵御来自气候和害虫的干扰和入侵。

不管怎样，生态系统稳定性的问题非常复杂。首先，不是所有的生态学家都赞同“稳定”的含义。稳定性可以简单地定义为缺乏变化。如果是这样的话，顶极群落将被视为最稳定的，因为根据定义，他们随着时间推移而变化得最少。另外，稳定性也可以界定为生态系统在经历了严重破坏之后回复原貌的速度，比如火灾。这种稳定性也被称作弹性。在这种情况下，顶极群落将是最脆弱和最不稳定的，因为他们可能需要数百年时间才能恢复到顶点状态。

即使是这种被定义为简单地缺乏变化的稳定性并非总是与最多样的物种联系起来。至少在温带地区，会经常在演替过程中发现最多物种，而不是在顶极群落中。例如，红杉树林一旦成熟，其中的物种数量以及单个物种的数量都会减少。一般来说，多样性本身并不能保证稳定性(事实上正相反)，生态系统的数学模型也可以得出同样的结论。一个更复杂的系统可能比一个简单的系统更容易被破坏(一个十五速的赛车比一个孩子的三轮车更容易损坏)。

生态学家们更想弄清楚到底哪些因素有助于促成群落的恢复，因为世界各地的顶极群落都因为人类活动而遭受到严重的损坏或毁坏。就像美国西北部圣海伦火山的猛烈喷发所造成的破坏，在人类活动对环境造成的破坏面前也相形见绌。我们必须了解对群落抵抗、破坏和恢复来说哪些是最重要的。

现在的很多生态学家们认为，顶极群落相对长期的稳定性并非来自于多样性，而是来自环境的“补缀”，随处变化的环境比始终如一的环境更有利于多种有机体的生存。当地物种灭亡后，马上就会被相邻群落的移民取代。即便是另一种不同的物种，他们也可以填补那些已灭绝生物的空缺，并保持食物网的完整。

托福阅读TPO3(试题+答案+译文)第3篇:The Long-Term Stability of Ecosystems

篇8：托福阅读TPO28(试题+答案+译文)第:Groundwater

托福阅读原文

【1】Most of the world’s potable water—freshwater suitable for drinking is accounted for by groundwater, which is stored in the pores and fractures in rocks. There is more than 50 times as much freshwater stored underground than in all the freshwater rivers and lakes at the surface. Nearly 50 percent of all groundwater is stored in the upper 1,000 meters of Earth. At greater depths within Earth, the pressure of the overlying rock causes pores and cracks to close, reducing the space that pore water can occupy, and almost complete closure occurs at a depth of about 10 kilometers. The greatest water storage, therefore, lies near the surface.

Aquifers, Porosity and Permeability

【2】Groundwater is stored in a variety of rock types. A groundwater reservoir from which water can be extracted is called an aquifer. We can effectively think of an aquifer as a deposit of water. Extraction of water depends on two properties of the aquifer: porosity and permeability. Between sediment grains are spaces that can be filled with water. This pore space is known as porosity and is expressed as a percentage of the total rock volume. Porosity is important for water—storage capacity, but for water to flow through rocks, the pore spaces must be connected. The ability of water, or other fluids, to flow through the interconnected pore spaces in rocks is termed permeability. In the intergranular spaces of rocks, however, fluid must flow around and between grains in a tortuous path; this winding path causes a resistance to flow. The rate at which the flowing water overcomes this resistance is related to the permeability of rock.

【3】Sediment sorting and compaction influence permeability and porosity. The more poorly sorted or the more tightly compacted a sediment is, the lower its porosity and permeability. Sedimentary rocks—the most common rock type near the surface—are also the most common reservoirs for water because they contain the most space that can be filled with water. Sandstones generally make good aquifers, while finer-grained mudstones are typically impermeable. Impermeable rocks are referred to as aquicludes. Igneous and metamorphic rocks are more compact, commonly crystalline, and rarely contain spaces between grains. However, even igneous and metamorphic rocks may act as groundwater reservoirs if extensive fracturing occurs in such rocks and if the fracture system is interconnected.

The Water Table

【4】The water table is the underground boundary below which all the cracks and pores are filled with water. In some cases, the water table reaches Earth’s surface, where it is expressed as rivers, lakes and marshes. Typically, though, the water table may be tens or hundreds of meters below the surface. The water table is not flat but usually follows the contours of the topography. Above the water table is the vadose zone, through which rainwater percolates. Water in the vadose zone drains down to the water table, leaving behind a thin coating of water on mineral grains. The vadose zone supplies plant roots near the surface with water.

【5】Because the surface of the water table is not flat but instead rises and falls with topography, groundwater is affected by gravity in the same fashion as surface water. Groundwater flows downhill to topographic lows. If the water table intersects the land surface, groundwater will flow out onto the surface at springs, weather to be collected there or to subsequently flow farther along a drainage. Groundwater commonly collects in stream drainages but may remain entirely beneath the surface of dry stream-beds in arid regions. In particularly wet years, short stretches of an otherwise dry stream-bed may have flowing water because the water table rises to intersect the land surface.

[Glossary]

Sediment: materials (such as sand or small rocks) that are deposited by water, wind, or glacial ice.

Topography: the shape of a surface such as Earth’s, including the rise and fall of such features as mountains and valleys.

托福阅读试题

1.In paragraph 1, why does the author mention ”the pressure of the overlying rock“?

A.To show how water can be forced deep under Earth's surface.

B.To show why groundwater is more plentiful than surface freshwater.

C.To correct a commonly made error about the location of groundwater.

D.To explain why most groundwater lies near Earth's surface.

2.According to paragraph 1, groundwater differs from the water in riversand lakes in terms of its

A.portability.

B.usefulness.

C.abundance.

D.cost.

3.The word ”extracted“ in the passage(paragraph 2)is closest in meaning to

A.used.

B.poured.

C.removed.

D.kept out.

4.The word ”termed“ in the passage(paragraph 2)is closest in meaning to

A.considered.

B.called.

C.limited to.

D.caused by.

5.According to paragraph 2, what does porosity determine?

A.The rate at which the aquifer's water overcomes resistance to flow.

B.The amount of water that the aquifer can hold.

C.The likelihood that fractures and joints will occur in the aquifer.

D.The depth underground at which the aquifer lies.

6.According to paragraph 2, what is the relationship between permeability and porosity?

A.The more pores a rock has, the higher its porosity but the lower its permeability.

B.Rocks with many internal spaces that are not connected with each other will have high porosity but low permeability.

C.If water flows through a rock easily, it has high permeability but low porosity.

D.Rocks that have high permeability have high porosity and vice versa.

7.The word ”compacted“ in the passage(paragraphy 3)is closest in meaning to

A.hard.

B.compressed.

C.heavy.

D.deeply buried.

8.According to paragraph 3, when can igneous rock serve as an aquifer?

A.When it has many connected fractures.

B.When it lies next to metamorphic rock.

C.When it lies relatively near the surface.

D.When it is crystalline.

9.The word ”coating“ in the passage(paragraph 4)is closest in meaning to

A.stream.

B.barrier.

C.amount.

D.layer.

10.Paragraph 4 implies which of the following about the rootsof plants?

A.They prevent water from reaching the vadose zone.

B.They mark the boundary between the vadose zone and the water table

C.They do not typically get their water from the water table.

D.They help keep the water table from dropping farther.

11.Which of the sentences below best expresses the essential information in the highlighted sentence in the passage paragraph 5 ? Incorrect choices change the meaning in important ways or leave out essential information.

A.Groundwater only flows out of the ground if the water table intersects the land surface.

B.If the land surface and the water table intersect, groundwater can flow underground.

C.Groundwater may be drained if springs occur where the water table intersects the land surface.

D.Where the water table meets the land surface, groundwater flows out through surface springs.

12.Paragraph 5 implies which of the following about the level of the water

A.It may rise or fall from year to year, depending on annual rainfall.

B.It does not vary in arid regions.

C.It rarely intersects the land surface of most regions.

D.It is unrelated to the rate at which groundwater flows.

13. Look at the four squares [■] that indicate where the following sentence could be added to the passage.Where would the sentence best fit? This is a consequence of the slow rate of movement of the groundwater, which often prevents the water table from attaining a flat (horizontal) level.

The water table is the underground boundary below which all the cracksand pores are filled with water. In some cases, the water table reaches Earth's surface, where it is expressed as rivers, lakes and marshes. ■【A】Typically,though,the water table may be tens or hundreds of meters below the surface. ■【B】The water table is not flat but usually follows the contours of the topography. ■【C】Above the water table is the vadose zone, through which rainwater percolates. ■【D】Water in the vadosezone drains down to the water table, leaving behind a thin coating of water onmineral grains. The vadose zone supplies plant roots near the surface withwater.

14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.

Most of the world's potable water is stored as groundwater in the poresand fractures of underground rock, much of it at depths of less than 1,000 meters.

A.Sedimentary rock may make poor aquifers because of tightly compacted sediment, which reduces porosity and permeability.

B.Porosity is a measure of the empty space within rock while permeability measures the degree to which water can flow freely through rock.

C.In arid regions, the water tables remain at a constant level far below the surface, preventing stream-beds from filling up even during wet years.

D.Groundwater reservoirs are characterized by the porosity and permeability of the rock in which they lie, and these factors vary according to the type of rock.

E.The vadose zone is typically dry because water does not stay in it, but instead percolates down to aquifers below or drains out through springs and streams.

F.Although the water table usually follows the contours of the land surface, its level may vary from year to year and may intersect to the surface in places.

托福阅读答案

1.在高亮部分的描写之后，本段的最后一句出现了，therefore。这里也是在说the pressure of the overlying rock导致的结果，也就是文章提到它的目的。其结果是，大部分的水储都在比较表面的地方。所以其目的就是要解释为什么水都在表面的地方。

2.对应原文第二句话，也就是将地下水和江河湖泊水进行比较的那句话。原句说more than 50 times。就证明是地下水的水量大。这里A是饮用性，原文并没有说江水不能喝。B是有用，同理。D是代价。这个就更没提到了。所以答案为C丰富。

3.extract本身是汲取，取出的意思。从原文后面一句话可以推测，因为后面说储水土层可以看作是对一笔水存款，所以前面应该是说可以取出。另外这个词的词缀ex-本身就有出的意思。那么A是使用，B是泼出，C是移动，D是隔离在外。

4.term作名词是术语，这个很常用。而这里用了其动词否定形式，那么应该是…被术语为，也就是被命名为。那么A是认为，B是叫做，C是限制于，D是由于。所以应该选B。

5.A决定于permeability of rack，对应本段最后一句。B正确，对应本段第七句(porosity is important for water-storage capacity)，这句话只要根据porosity定位就很好找。C和porosity没有直接关系。D原文就没提到。

6.对应本段第一句和第二句，即sorting和compaction会共同影响permeability，结合上一段的最后一句理解，多孔性分为两种情况，一种是孔多但是互相不联通，这时permeability不高;另一种是孔多并且互相联通，那么porosity高的同时permeability也会高。因此选择B。其他几个选项的叙述都不完整。这两者的关系并不是简单的正比例。

7.compact是压缩，紧密的意思。通过后面的and的并列内容可以推出其词义，因为and后面说rarely contain space，那就是说中间的空间很小。所以选择B压缩的。A是坚硬，C是重的，D是深埋的。

8.对应本段文章最后一句”even igneous rocks may act as groundwater…"后半句给出的就是答案，那么它说的是要有fractures并且要interconnected。所以选A。

9.Coating本来是外衣，和涂层的意思。那么A是溪流，B是障碍物，C是数量，D是层。所以D符合。

10.根据plant roots定位到本段最后一句。说vadose zone给植物根部提供了水。选项A，B，D都没提到。而只有C没有错误，因为plant roots是从vadose zone汲取的水份，而不是water table。所以选C。

11.A选项缺少了spring这个条件;B，C选项不正确。D包含了原文所有的主干部分，正确。

12.根据这段最后两句对于wet year的描写可以得出根据降雨量不同，地下水位是有变化的。所以A正确。B不正确，原文明显写到在arid regions降雨量多时干燥的溪床会有水。C也不对，整段都有大篇幅在写和land surface的intersects。D原文没提到。

13.要插入的句子说this is a consequence，那么this一定指代什么，根据后半句可以知道指代的内容应该与地下水位不是平面有关。所以C的位置符合，因为前面一句说地下水位不是平面。

14.A 错误，对应文章第三段的第三句有关于sedimentary rock的描写。根据原文，sedimentary rock是很好的aquifers，B正确，对应第二段的前四句。C正确，对应原文第二段。D错误，vadose zone中会留下thin coating所以还是会湿润。对应原文第四段。E错误，water table本非remain at a constant level，根据倒数第二句，地下水位有时会和地表交叉的。F正确，对应原文最后一段。

托福阅读译文

【1】世界上绝大部分饮用水----可以饮用的淡水----都是地下水，它们储藏在岩石孔隙和裂缝中。储藏于地下的淡水是地表淡水河流和湖泊中总水量的50倍。大约50%的地下水存在于地下深1000m以内的地层中。随深度增加，上覆岩层压力使岩石孔隙和裂缝闭合，减少了水的储存空间，而超过10公里深的地下孔隙几乎全部闭合。因此绝大部分水储存于接近地表的地层中。

水层，孔隙度和渗透率

【2】地层水储存在多种岩石中。可以取出的地下水的聚集层叫做水层。我们可以认为水层即水的聚集地层。从地层中取水取决于水层的两个因素：孔隙度和渗透率。沉积颗粒之间的空间可以储存水，这种孔隙空间由孔隙度表征。孔隙度是岩石孔隙体积与总体积的百分比。孔隙度对地层储水能力尤为重要，但欲使水从岩石中流出，孔隙之间必须相互连通。水或其它流体从相互连通的孔隙中流动的能力即为渗透率。在粒间孔发育的岩石中，流体必须在颗粒周围的曲折通道中流动;这种曲折通道会对流动产生阻力。水克服阻力流动的速率与岩石渗透率相关。

【3】沉积物的分选性和压实程度影响其渗透率和孔隙度。岩石分选越差或压实越紧则其孔隙度和渗透率越低。沉积岩----地表最常见的岩石----也是最常见的水储集层，因为它们常带有最多的可以储水的孔隙空间。砂岩一般是最好的储水层，但小颗粒的泥岩则通常不可渗透。不渗透岩层都称为隔水层。火成岩和变质岩压实更紧，通常有结晶，并几乎没有粒间孔隙。但是即便是火成岩和变质岩也可因裂缝大量发育并相互连接而成为储水层。

地下水位

【4】地下水位指地层岩石裂缝和孔隙充满水的边界。某些情况下，地下水位可能到达地表，在那里它以河流、湖泊或沼泽地的形式存在。但通常情况下地下水位位于地面数十或数百米以下。地下水位不是水平的，而是通常沿着地势起伏。地下水位以上称为包气带，在这里降水得以过滤。包气带中的水会沉降到地下水位，只在矿物颗粒表面留下一层水膜。包气带为地表附近植物根部提供水分。

【5】因为地下水位表面并非水平，而是沿着地势起伏，地下水和地表水受到重力影响的模式相同。地下水沿着下倾地层流向地势低洼处。如果地下水位与地表相交，地下水将以喷泉的形式流出地面，要么就地聚集，要么沿排水通道流向更远的地方。地下水通常在小溪中聚集，但在干旱地区也可能全部停留在干涸河床下。在特定湿润的年月里，一段干涸的河床下游可能有水流动，因为地下水位抬升到了那里的地表以上。

托福阅读TPO28(试题+答案+译文)第1篇:Groundwater

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