请教: 鲸鱼喝海水的那道JJ

fg_bamboo

题目出处一时找不到, 斑斑见谅啊, 这里就把整个题目贴出来:

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

答案为什么选A呢? 意思不明白...

fg_bamboo

仔细读了答案,明白了, 斑斑删除这个帖子吧, 不好意思了哦

fg_bamboo

to blue_yuwen:

题目讲: 6million 年前Whale生活在淡水里. 不到1million年后, Whale有了可以特殊的kidney可以喝海水了.虽然化石证据表明一些早期的没有这样的kedney的Whale有时在海水里, 但是它们肯定是经常回到淡水河里喝水.

答案A说: 在之前6million 到5million间, Whale的化石在与原始Aisa有一片海域相隔的陆地上没有找到.

这就说明Whale那个时候是不能喝海水的(所以化石不能在海洋那边的陆地上找到), 被题干最后的原题结论所支持.

[此贴子已经被作者于2007-3-7 18:14:39编辑过]

Bobcat

why D is wrong?

gonghao

the difference between the whale that drank salt-water and those drank fresh water is irrevalent to this question.

The argument drawn an conculsion based on an assumption that what it said in the first sentence is the truth.  By then, the conculsion stands.

A is the provement to this strengthen point.