OG01-The Origins of Cetaceans

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                           OG01-The Origins of Cetaceans
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 live young. Their 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 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 and cetaceans.
1：C被观察是哺乳动物
2:  C的特征
3：缺少（the absence of）和（the presence of）形成前后对比，并且重点在于后面，【并不能隐藏他们与陆地哺乳动物的关联】
*对应题1
4：however 【进行转折】 后面将C和Sea Otter进行了对比，很难猜出早期的C长什么样
*对应题2
5：灭绝 but【转折】还是有化石记录关于C留存下来
6: 提出疑问，陆地（walking）哺乳动物和水生（swimming）鲸鱼直接的联系？
7：【倒装句 主语是fossils】这个问题知道最近的化石被发现才得以证实了关于陆地哺乳动物和C的迁移
1. In paragraph 1, what does the author say about the presen6ce of a blowhole in cetaceans?
○It clearly indicates that cetaceans are mammals.
○It cannot conceal the fact that cetaceans are mammals.
○It is the main difference between cetaceans and land-dwelling mammals.
○It cannot yield clues about the origins of cetaceans.
【作者意图题】
A：清晰的暗示；而原文表述的是【没有隐藏】
B: 对的；其中conceal=disguise
C: 在C和陆地生物之间的主要不同；而原文表述的【无法隐藏C和陆地生物之间的关系】
D: 不能分清线索关于C的起源；【原文第一段都在讲述探寻C的原始祖先与哺乳动物的关系】
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 them.
○They lived in the sea only.
○They did not leave many fossil remains.
【推断题】
A: 对的；【因为太难以想象原始鲸鱼的样子，那对比来说SO 就很好想象】
B：他们有很多数量；【原文中间没有提及】
C:  他们只在海里生活【有only这样的绝对词首先一定要小心，其次原文both on land and at sea，表明他们海陆都可以生活】
D:他们没有留下很多化石【原文并没提及】

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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 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. 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 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 bred and gave birth on land.
1: 这些化石组成的完整（complete）的头盖骨，一个灭绝的族群关于现代C的祖先
2：（Although）尽管头盖骨有限但是P还是提供了珍贵的资料关于C的起源
*对应题3
3：这些头盖骨和C相像（but）但是下巴少了一个扩大的空间，这些空间是用来....的在现代鲸鱼的身上
*对应题4
4:  P可能耳朵的开合来接受声音
*对应题4
5：头盖骨还没有洞，其他的C用洞来潜水，但是P却没有
6：(however)但是，另一个特点是P的迁移形成于群组....
7：【总结】这就暗示了P在浅水吃鱼并且还没适应海洋
*对应题5
8：【更总结】P是陆地生物
3. The word “precious” in the passage is closest in meaning to
○exact
○scarce
○valuable
○initial
【词汇题】
C:Precious=valuable 珍贵的
4. Pakicetus and modern cetaceans have similar
○hearing structures
○adaptations for diving
○skull shapes
○breeding locations
【事实信息题】
A：听力结构；原文【P可能耳朵的开合来接受声音，却没说C可以】
B：适应潜水了；原文【其他的C用洞来潜水，但是P却没有】
C：对的；【P这些头盖骨和C相像； The skull is cetacean-like】
D：生产定位；原文【P已经被确定是陆生，而现在C是水生】
It probably bred and gave birth on land.
5. The word “It” in the passage refers to
○Pakicetus
○fish
○life
○ocean
【指代题】
A:上句刚说P如何如何，明显指代P

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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 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. Such legs would have been far too small to have supported the 50-foot-long on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.
1：另一个发现B
2：一些B的骨头，在一个由TS海沉积物，现在是沙漠的地方被发现了
*对应题6
3：B活在P之后【P<B】
4：很多不完整的骨头（incomplete）【对应上文的完整的】被发现了，他们有完整的后腿和三个小脚趾
*对应题7
5：这样的腿都是太小以至于不能走50步子长的路（too...to）
6：【总结】B是完全的海洋生物
*对应题7/*对应题8
6. The word “exposed” in the passage is closest in meaning to
○explained
○visible
○identified
○located
【词汇题】
B:Expose 意味着暴露，在这里看做是可见；exposed=visible
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 Pakicetus
○was able to swim well
○could not have walked on land
A: 比An迟出现 【这段根本没有提及】
B：B和P出现在同一个时期；原文中说【是after Pakicetus】
C：可以很好的游泳；【原文没有提到】
D：不能在陆地上行走；而原文说【possibly nonfunctional hind legs 没有功能的后腿】
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
【推理题】
A：在陆地；原文已经总结【B是完全的海洋生物】
B：又在海上，又在陆地；原文已经总结【B是完全的海洋生物】
C：在浅水；【P才在浅水；B在海里】
D：对的；在海洋环境中

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Paragraph 5: An even more exciting find was reported in 1994, also from 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 strong 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 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 that linked life on land with life at sea
1：【主旨句，却不重要】一个更令人兴奋的发现出现了，从P之后
2：【发现了A】An这个还是在发现p这个地方被发现了
3: 【P<An<B】
4：【后面都在讨论腿】化石幸运的包含（portion）部分后腿
*对应题9
5：腿很强壮
6：这些腿就是适合陆地生活和海里生活的
7：这种鲸鱼有尾巴并且缺少f，还是想现代的C一样运动
8：（however）但是背骨头结构，证明An还是能像modern C一样运动，尽管没有f
*对应题10
9：而腿的作用就是蹬水
*对应题11
10：所以An在陆地上会想海狮一样走
11：【总结】An是一种鲸鱼链接海洋和陆地
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 scientists to reconstruct a complete skeleton of the whale.
○Until that time, only the front legs of early whales had been discovered.
【事实信息题】
A：化石的腿是罕见的；【原文没有提及】
B：对的；腿提供了关于C变迁的重要信息
C：这个发现允许科学家们重建完整的鲸鱼的骨头；原文并没有提及
D：直到那时，前腿才被找到；原文是一直说【hind leg 后腿】
The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing.
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 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 like 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.
【句子简化题】
这个背骨头结构，证明An还是能像modern C一样运动上上下下的游动，尽管没有f
A：尽管A能上上下下的游，可是还是没有背骨
B：A的背骨，能够游泳，提供了A没有f的证据
C:尽管A没有f，他的背骨结构显示他能像现在的鲸鱼一样游泳
D:对的；
11. The word “propulsion” in the passage is closest in meaning to
○staying afloat
○changing direction
○decreasing weight
○moving forward
【词汇题】
D：propulsion=moving forward 向前移动

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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 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 where 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.

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 scientists for ages.
Where would the sentence best fit?
【指代题】
需要找前句question；后句puzzled scientists for ages.这样的地方进行插入；【毫无疑问就是B】
13. 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.

This passage discusses fossils that help to explain the likely origins of cetaceans—whales, porpoises, and dolphins.

Answer Choices
○Recent discoveries of fossils have helped to show the link between land mammals and cetaceans.
○The discovery of Ambulocetus natans provided evidence for a whale that lived both on land and at sea.
○The skeleton of Basilosaurus was found in what had been the Tethys Sea, an area rich in fossil evidence.
○Pakicetus is the oldest fossil whale yet to be found.
○Fossils thought to be transitional forms between walking mammals and swimming whales were found.
○Ambulocetus' hind legs were used for propulsion in the water.
【多选题】
1读懂题目：This passage discusses fossils that help to explain the likely origins of cetaceans—whales, porpoises, and dolphins.讨论了化石解释了为啥C的起源会是哺乳动物呢？
2寻找对应选项
   A:(P1)
B:(p5)
C：an area rich in fossil evidence.错误
D：yet to be found.错误
E：(P5)
D: Ambulocetus' 错误

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************************************************************************************************************************************************若是有不对的地方，欢迎指正，谢谢各位