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TPO閲讀解析——THE ORIGINS OF CETACEANS

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. Their streamlined bodies, the absence of hind legs, and the presence of a fluke and blowhole  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. In paragraph 1, what does the author say about the presence of a blowhole in cetaceans?
  1. It clearly indicates that cetaceans are mammals.
  2. It cannot conceal the fact that cetaceans are mammals.
  3. It is the main difference between cetaceans and land-dwelling mammals.
  4. It cannot yield clues about the origin of cetaceans.

Correct Answer is B.

解析:儘管有blowhole這種標志性的東西,但是這還是不能掩蓋它是哺乳動物的事實,選B

 

  1. Which of the following can be inferred from paragraph 1 about early sea otters?
  1. It is not difficult to imagine what they looked like.
  2. There were great numbers of them.
  3. They lived in the sea only.
  4. They did not leave many fossil remains.

Correct Answer is A.

解析: …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. 説明first sea otter很好想象出樣子,同義替換envision相當於imaginenot easy替換為not difficult,故選A。這一題要注意問的是“early sea otters”,不是問的“sea otters”,看錯了有可能混選D,實際上D也沒有提到過,即使通過下一句推斷出化石不是很多,但是很牽强了,TOEFL不會去考察這麽不明顯的推斷。爲什麽這麽講,即使鯨類有一些化石,但不能通過這種對比推斷海獺類几乎沒有化石。

 

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.

 

archaeocyte 【名】原始生殖细胞;原始細胞(這個單詞不在TOEFL單詞之列)

Pakicetus 【名】巴基鲸

mesonychids 【名】中爪兽

 

  1. The word precious in the passage is closest in meaning to
  1. exact
  2. scarce
  3. valuable
  4. initial

Correct Answer is C.

解析:記住詞義。

 

  1. Pakicetus and modern cetaceans have similar
  1. hearing structures
  2. adaptation for diving
  3. skull shapes
  4. breeding locations

Correct Answer is C.

解析:原文提到“The skull is cetacean-like”直接決定選C。這一段問題是生詞太多了,在閲讀困難的情況下,相對來講,題目不會太難。

 

  1. The word It in the passage refers to
  1. Pakicetus
  2. fish
  3. life
  4. ocean

Correct Answer is A.

解析:這一題不可能選錯,你把BCD帶入讀一下就知道是錯的。

 

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 Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.

 

Basilosaurus 龙王鲸;背脊鲸

  1. The word exposed in the passage is closest in meaning to
  1. explained
  2. visible
  3. identified
  4. located

Correct Answer is B.

解析:記住詞義。一開始還想著帶入D選項好像也讀得通,但是就是不對。詞匯題最好還是通過記單詞的方式做完,通過分析句子推斷意思很容易出錯。

 

Ambulocetus natans 走鲸;走鲸属

  1. The hind leg of Basilosaurus was a significant find because it showed that Basilosaurus
  1. lived later than Ambulocetus natans
  2. lived at the same time as Pakicetus
  3. was able to swim well
  4. could not have walked on land

Correct Answer is D.

解析:記住,做題要核對答案正誤不可能跑到其他paragraph去核對,所以請耐心看完所有選項,像A選項出現了一個剛才沒讀到的東西,可以先放一放。原文提到“Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. 直接驗證了D選項。

 

  1. It can be inferred that Basilosaurus bred and gave birth in which of the following locations?
  1. On land
  2. Both on land and at sea
  3. In shallow water
  4. In a marine environment

Correct Answer is D.

解析:“Basilosaurus was undoubtedly a fully marine whale 直接告訴我們選D

 

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.Fluke: the two parts that constitute the large triangular tail of a whale.2.Blowhole: a hole in the top of the head used for breathing.

 

  1. Why does the author use the word luckily in mentioning that the Ambulocetus natans fossil included hind legs?
  1. Fossil legs of early whales are a rare find.
  2. The legs provided important information about the evolution of cetaceans.
  3. The discovery allowed scientists to reconstruct a complete skeleton of the whale.
  4. Until that time, only the front legs of early whales had been discovered.

Correct Answer is B.

解析:做這一題務必把最後一句讀完。然後回到原句“The fossil luckily includes a good portion of the hind legs. 我們知道A開頭的鯨魚有完整的後腿并且兩栖,同時我們也知道B開頭的鯨魚也有後腿,但是站不起來,所以只能生活在海洋,P開頭的是被認爲生活在陸地和淺水,但是沒有提及有沒有腿,只是很像鯨卻沒氣孔。PAB,陸地→兩栖→海洋。爲什麽說A錯,是因爲并非rare,他們特地説出一種種類的鯨是有後腿的,叫中爪獸,這種化石不會很少;也不可能選C,因爲C的這種説法在發現第一種巴基斯坦鯨的時候就已經出現了,那個時候獲得的是a complete skull of an archaeocyte,所以不可能選CD說只有前腿被發現,這也是錯的,3-4段都是發現有後腿了的,只是第三段不是説得特別明顯,中爪獸是一種四足食肉動物,而且原段也説了它不可能在水裏生活,那麽沒有腿是不可能的。因此,說A開頭的鯨魚的發現,彌補了P進化到B的空缺,因爲A是兩栖的。

這一題選B(實際上如果你有注意到第一段“How was the gap between a walking mammal and a swimming whale bridged? 也能聯想到)

 

  1. Which of the sentence below best express the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
  1. Even though Ambulocetus swam by moving its body up and down, it did not have a backbone.
  2. The backbone of Ambulocetus, which allowed it to swim, provides evidence of its missing fluke.
  3. Although Ambulocetus had no fluke, its backbone structure shows that it swam like modern whales.
  4. By moving the rear part of their bodies up and down, modern whales swim in a different way from the way Ambulocetus swam.

Correct Answer is C.

解析:句子改寫題。沒什麽好説的,這可能是最簡單的一題了。

 

  1. The word propulsion in the passage is closest in meaning to
  1. staying afloat
  2. changing direction
  3. decreasing weight
  4. moving forward

Correct Answer is D.

解析:記住詞義。propulsion推進力。

 

 

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.

 

  1. 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?

Click on a square [ ] to insert the sentence in the passage.

Correct Answer is B.

解析:因爲第一段直接出現了一個問句,所以毫無疑問,這一題選B

 

  1. Direction: 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 questions is worth 2 points.

This passage discusses fossil that help to explain the likely origin of cetaceans—whales, porpoises, and dolphins.

  1. Recent discoveries 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. Pakicetus is the oldest fossil whale yet to be found.
  5. Fossil thought to be transitional forms between walking mammals and swimming whales were found.
  6. Ambulocetus' hind legs were used for propulsion in the water.

Correct Answer is ABE.

解析:CDF都是細節,100%不選;所以很容易就選出了ABE正解。

 

 

*綠色字體表示生詞

*藍色字體表示TPO題選取的單詞

*紅色表示正確答案+多次重复的单词

 

主目錄:https://www.v2know.com/MainPage/Category/TOEFL

This article was last edited at 2021-05-20 20:30:21

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