托福TPO2Part2阅读原文及参考答案.docx

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1、托福TPO2Part2阅读原文及参考答案 托福TPO作为大家托福备考的模考工具，它的题目对我们有很大的参考价值，为了帮助大家备考，下面我给大家带来托福TPO2Part2阅读原文及参考答案，望喜爱。 托福TPO2Part2阅读原文 The Origins Of Cetaceans It should be obvious that cetaceans-whales, porpoises, and dolphins-are mammals. They breathe through lungs, not through gills, and give birth to live young. Th

2、eir streamlined bodies, the absence of hind legs, and the presence of a fluke1 and blowhole2 cannot disguise their affinities with land dwelling mammals. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is

3、not easy to envision what the first whales looked like. Extinct but already fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing until recently were fossils clearly intermediate, or transitional, between land mammals

4、and cetaceans. Very exciting discoveries have finally allowed scientists to reconstruct the most likely origins of cetaceans. In 1979, a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale. The fossil was officially named Pakicetus in honor of the country wh

5、ere the discovery was made. Pakicetus was found embedded in rocks formed from river deposits that were 52 million years old. The river that formed these deposits was actually not far from an ancient ocean known as the Tethys Sea. The fossil consists of a complete skull of an archaeocyte, an extinct

6、group of ancestors of modern cetaceans. Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales

7、. Pakicetus probably detected sound through the ear opening as in land mammals. The skull also lacks a blowhole, another cetacean adaptation for diving. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and c

8、etaceans. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably bred and gave birth on land. Another major discovery was made in Egypt in 1989. Several skeletons of another early whale, Basilosaurus, were found in sediments

9、left by the Tethys Sea and now exposed in the Sahara desert. This whale lived around 40 million years ago, 12 million years after Pakicetus. Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes. Su

10、ch legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs. An even more exciting find was reported in 1994, also from Pakistan. The now extinct whale Ambulocetu

11、s natans ("the walking whale that swam") lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus. The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like

12、those of a modern pinniped. The legs were certainly functional both on land and at sea. The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans. The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion o

13、f its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion. It was undoubtedly a whale that linked life on land with life at sea Flu

14、ke: the two parts that constitute the large triangular tail of a whale 1. "Blowhole: a hole in the top of the head used for breathing Paragraph 1: It should be obvious that cetaceans-whales, porpoises, and dolphins-are mammals. They breathe through lungs, not through gills, and give birth to li

15、ve young. Their streamlined bodies, the absence of hind legs, and the presence of a fluke3 and blowhole4 cannot disguise their affinities with land-dwelling mammals. However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at

16、sea), it is not easy to envision what the first whales looked like. Extinct but, already fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing until recently were fossils clearly intermediate, or transitional, between

17、land mammals and cetaceans. 托福TPO2Part2阅读题目 Directions: Mark your answer by filling in the oval next to your choice. 1. In paragraph 1, what does the author say about the presence of a blowhole in cetaceans? It clearly indicates that cetaceans are mammals. It cannot conceal the fact that cetaceans a

18、re mammals. It is the main difference between cetaceans and land-dwelling mammals. It cannot yield clues about the origins of cetaceans. 2. Which of the following can be inferred from paragraph 1 about early sea otters? It is not difficult to imagine what they looked like There were great numbers of

19、 them. They lived in the sea only. They did not leave many fossil remains. Paragraph 3: The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetacean

20、s. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales. Pakicetus probably detected sound through the ear opening as in land mammals. The skull also lacks a blowhole, another cetacean adaptation f

21、or diving. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and cetaceans. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably br

22、ed and gave birth on land. 3. The word precious in the passage is closest in meaning to Exact Scarce Valuable Initial 4. Pakicetus and modern cetaceans have similar Hearing structures Adaptations for diving Skull shapes Breeding locations 5. The word it in the passage refers to Pakicetus Fish Life o

23、cean Paragraph 4: Another major discovery was made in Egypt in 1989. Several skeletons of another early whale, Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert. This whale lived around 40 million years ago, 12 million years after Pakicetus. Many incom

24、plete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes. Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with p

25、ossibly nonfunctional, or vestigial, hind legs. 6. The word exposed in the passage is closest in meaning to Explained Visible Identified Located 7. The hind leg of Basilosaurus was a significant find because it showed that Basilosaurus Lived later than Ambulocetus natans Lived at the same time as Pa

26、kicetus Was able to swim well Could not have walked on land 8. It can be inferred that Basilosaurus bred and gave birth in which of the following locations On land Both on land and at sea In shallow water In a marine environment Paragraph 5: An even more exciting find was reported in 1994, also from

27、 Pakistan. The now extinct whale Ambulocetus natans ("the walking whale that swam") lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus. The fossil luckily includes a good portion of the hind legs. The legs were st

28、rong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea. The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans. The structure of the backbone shows, however, that Ambulocetus swam like

29、 modern whales by moving the rear portion of its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion. It was undoubtedly a whale th

30、at linked life on land with life at sea 9. Why does the author use the word luckily in mentioning that the Ambulocetus natans fossil included hind legs? Fossil legs of early whales are a rare find. The legs provided important information about the evolution of cetaceans. The discovery allowed scient

31、ists to reconstruct a complete skeleton of the whale. Until that time, only the front legs of early whales had been discovered. 10. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways

32、 or leave out essential information. Even though Ambulocetus swam by moving its body up and down, it did not have a backbone. The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke. Although Ambulocetus had no fluke, its backbone structure shows that it swam li

33、ke modern whales. By moving the rear parts of their bodies up and down, modern whales swim in a different way from the way Ambulocetus swam. 11. The word propulsion in the passage is closest in meaning to Staying afloat Changing direction Decreasing weight Moving forward Paragraph 1: Extinct but alr

34、eady fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans.Very exciting discoveries have finally allowed scientists

35、 to reconstruct the most likely origins of cetaceans. In 1979, a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale. 12. Look at the four squares that indicate where the following sentence can be added to the passage. This is a question that has puzzled sci

36、entists for ages. Where would the sentence best fit? 13-14. 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

37、 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. This passage discusses fossils that help to explain the likely origins of cetaceans-whales, porpoises, and dolphins. Answer Choices 1. Recent discoveries

38、of fossils have helped to show the link between land mammals and cetaceans. 2. The discovery of Ambulocetus natans provided evidence for a whale that lived both on land and at sea. 3. The skeleton of Basilosaurus was found in what had been the Tethys Sea, an area rich in fossil evidence. 4. Pakicetu

39、s is the oldest fossil whale yet to be found. 5. Fossils thought to be transitional forms between walking mammals and swimming whales were found. 6. Ambulocetus' hind legs were used for propulsion in the water 托福TPO2Part2阅读答案 参考答案： 1、2 2、1 3、3 4、3 5、1 6、2 7、4 8、4 9、2 10. 3 11. 4 12. 2 13-14. 1 2

40、 5 托福TPO2Part2阅读原文翻译 沙漠已经占据了地球表面积约四分之一，而且最近几十年正以惊人的速度扩张。沙漠化是指类似沙漠的环境漫延到原本并非沙漠的区域。据估计，地球表面另外四分之一的地方正面临沙漠化威逼。 沙漠化主要通过以下过程实现：首先自然植被不断削减，随后风力和雨水加速了土壤的腐蚀。有的时候松散的土壤全部被风刮走，留下石质化的表层;其它状况下细小的沙粒可能会被吹走，而正常沙粒大小的砂子不断积累，从而形成移动的沙丘或者沙脊。 即便是在保留了土壤表层的区域，植被削减也已成为土壤大量吸取地下水的实力下降的典型因素。雨水对松散土壤的冲击会把细小的粘土颗粒冲到土壤空隙中，封闭了土壤并降低土

41、地表层水的渗透率。地表对水的汲取急剧削减，大量水资源流失，因此土壤的腐蚀率也随即增加。地表汲取水分的实力进一步弱化使得土壤更加干燥，导致植被的进一步流失，于是便形成了土壤沙漠化的恶性循环。 在一些地方，沙漠面积的扩大很大程度上归因于干燥的气候条件。在过去的几千年里，不断增加的温室效应使得一些地方干旱问题愈发严峻。倘如空气污染带来的温室效应接着恶化，沙漠化进程会在将来数十年内加速实现。 然而，可以确定的是，大部分地区沙漠化主要都是由于人类活动造成，而非自然条件导致。沙漠边缘的半干旱土地所处的生态平衡环境特别脆弱，环境压力持续增加，而这些半干旱区域适应环境压力的实力极其有限。人口数量的增加使得人们

42、不断向土地施压，依其供应食物和燃料。在潮湿的季节里，土地也许能够应付这些压力。但是在干旱的季节里，在沙漠周边的土地上，存在着这样一个非常普遍的现象：人类对土地施加的压力远远超过了土地自身减压的实力，因此最终形成了沙漠。 导致沙漠化的主要因素有四个：过度种植，过度放牧，过分砍伐，过度浇灌。由于人口密度增加，人们对粮食作物的种植已经扩展到日益干燥的区域进行。这些区域很有可能常常会发生干旱，所以农作物种植失败是很正常的事情。大多数农作物的种植须要事先移除自然植被，而农作物欠收后又会留下大面积荒地，特别简单被风力和雨水侵蚀。 在半干旱地区，草坪是主要的自然植被，家畜饲养是当地的一项主要经济活动。在一个

43、地区过量饲养家畜会导致植被覆盖面积削减，土地被大量践踏和碾碎。通常，随之而来的就是土地硬化和加速侵蚀。 在许多国家木材是用来做饭和加热的最主要燃料。人口增加带来的压力促使人们大量砍伐木材，导致很多城市和乡村四周大面积树木和灌木削减。同时人们大量运用烘干的动物排泄物作为替代燃料同样对土壤不利，因为这些宝贵的土壤成分调整剂和植物养分资源将不会再回来至土壤当中。 造成土地沙漠化的最终一个主要人为因素在于人类过度浇灌导致土壤的盐碱化。浇灌多余的水渗透到地下水位。假如没有排水系统的存在，那么地下水位上升，把溶解的盐分带到土壤表面。水分蒸发后，盐分留在了表面，形成白色的地壳层，这一地壳层阻挡了空气和水接触

44、地底下的土壤。 沙漠化问题异样严峻，这是因为有佷广袤的地区和数量浩大的人群都受到了沙漠化的影响，而且要想逆转沙漠化的进程甚至减缓沙漠化的速度都面临着巨大的困难。一旦土壤被侵蚀，须要再经过几百到上千年的时间才会产生新的土壤。那些大量土壤仍保存完好的地方，亟需一个严谨而有力的爱护政策和植被覆盖安排来爱护现有土地。 托福TPO2Part2阅读原文及参考答案本文来源：网络收集与整理，如有侵权，请联系作者删除，谢谢！第20页 共20页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页第 20 页 共 20 页