托福阅读：TPO2(The Origins Of Cetaceans)原文及答案

　　题目解析：

　　1. In paragraph 1, what does the author say about the presence of a blowhole in cetaceans?

　　(Factual Information Question)

　　A.It clearly indicates that cetaceans are mammals.

　　B.It cannot conceal the fact that cetaceans are mammals.

　　C.It is the main difference between cetaceans and land-dwelling mammals.

　　D.It cannot yield clues about the origins of cetaceans.

　　相关原句：

　　Their streamlined bodies, the absence of hind legs, and the presence of

　　a fluke and blowhole cannot disguise their affinities with land dwelling mammals.(Paragraph 1)

　　本题解析：

　　cannot disguise…意为“不能掩盖…”，因此 “the presence of blowhole cannot disguise their affinities with land dwelling mammals”意思是“具有blowhol(出气孔)并不能掩盖这一事实：鲸类动物和陆栖哺乳动物有姻亲关系(affinities)”;B选项中cannot conceal (不能隐藏)恰好与 cannot disguise相吻合，并指出鲸类动物是哺乳动物的事实，因此选择B。

　　正确答案：

　　B

　　2. Which of the following can be inferred from paragraph 1 about early sea otters?(Inference Question)

　　A.It is not difficult to imagine what they looked like

　　B.There were great numbers of them.

　　C.They lived in the sea only.

　　D.They did not leave many fossil remains.

　　相关原句：

　　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. (Paragraph 1)

　　本题解析：

　　unlike意为“与…不同”，it is not easy to envision意为“不容易设想…”。本句为转折，即“与海獭(sea otters)不同，人们很难想象最初鲸类的样貌”，因此逻辑取非得出“sea otters的样貌不难想象”，选择A。

　　正确答案：

　　A

　　3. The word precious in the passage is closest in meaning to (Vocabulary Question)

　　A.Exact

　　B.Scarce

　　C.Valuable

　　D.Initial

　　相关原句：

　　Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans.(Paragraph 3)

　　本题解析：

　　precious意为“珍贵的，有价值的”，后文种种由该化石得出的科研结论也表明P化石极有科学价值，与valuable同意。因此选择C。

　　正确答案：

　　C

　　4. Pakicetus and modern cetaceans have similar(Factual Information Question)

　　A.Hearing structures

　　B.Adaptations for diving

　　C.Skull shapes

　　D.Breeding locations

　　相关原句：

　　The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. (Paragraph 3)

　　本题解析：

　　根据原句得出P化石与现代鲸类的祖先(archaeocyte)拥有同样的完整头骨(a complete skull)，可推出P与现代鲸类头骨应该类似。因此选择C。

　　此题亦可用排除法：

　　A. “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. Pakicetusprobably detected sound through the ear opening as in land mammals.”该句指出P化石的颚骨(jawbones)缺少鲸类动物拥有的由脂肪和油脂填充的扩充性空间(enlarged space

　　that is…)，听力构造不同，并猜测它应该通过耳孔(the ear opening)接受声音，排除A。

　　B. “The skull also lacks a blowhole, another cetacean adaptation for diving.”该句明确指出P头骨缺少出气孔(blowhole)，同鲸类潜水构造不同，排除B。

　　D.

　　It

　　probably bred and gave birth on land.关于P在何处繁殖尚无定论，文章猜测(probably)在陆地(give birth on land)，排除D。

　　正确答案：

　　C

　　5. The word it in the passage refers to(Reference Question)

　　A.Pakicetus

　　B.Fish

　　C.Life

　　D.ocean

　　相关原句：

　　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. (Paragraph 3)

　　本题解析：

　　科学家猜测Pakicetus可能靠浅水区鱼类为食并尚未适应海洋生活，由此得出“很可能在陆地繁殖”的主体“it”正是指Pakicetus。因此选A。

　　正确答案：

　　A