Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago....

题目信息

Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago. Not until about ten million years later did species of whales develop specialized kidneys enabling them to drink salt water. Although fossil evidence shows that some early whale species that lacked such kidneys sometimes swam in the Earth's saltwater oceans, these species must have had to return frequently to freshwater rivers to drink.

Which of the following is most strongly supported by the information given?

A:Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean.

B:Among whale fossils that date from later than about fifty million years ago, none are fossils of whale species that drank only fresh water.

C:Fossils of whale species that drank fresh water will not be found in close proximity to fossils of whale species that drank salt water.

D:The earliest whales that drank salt water differed from fresh-water-drinking whales only in their possession of specialized kidneys.

E:Between sixty million and fifty million years ago, the freshwater lakes and rivers in which whales originated were gradually invaded by salt water.

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正确答案： A:Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean.

文中说鲸鱼起源于6000万年前自淡水湖泊。知道1000万前才生出了肾，使它们能够喝咸水。结论说尽管有证据表明有一些早起的没有肾的鲸类可以游到咸水海洋里，但是它们不得不经常回到淡水河里喝水。

A正确。说在六千五百万年前，在与Asia隔的很远的大陆上没有鲸鱼化石的发现。--- 这就说明鲸鱼游不了那么远，从而支持了鲸鱼需要经常回淡水去喝水的结论；

B在五千万年以后发现的鲸鱼化石中，没有只喝淡水的鲸鱼化石。--- 文中开头说了是起源于淡水的。并且即使正确，也不能支持结论，排除

C喝淡水的鲸鱼的化石和喝咸水的鲸鱼的化石很不一样。--原文没说过，无关

D最早期的喝咸水的鲸鱼和喝淡水的鲸鱼唯一不同之处在于有肾脏。无关

E鲸鱼起源的淡水湖逐渐被咸水侵蚀--- 没说，排除

笔记