gwd-12-29请教一下

泡泡老婆

搜了半天，好像是没有这一题的了，所以麻烦大虾们帮忙确认一下了。偶选的是E,答案咋是A呢？A应该是错的吧？

The Earth’s rivers constantly carry dissolved salts into its oceans. Clearly, therefore, by taking the resulting increase in salt levels in the oceans over the past hundred years and then determining how many centuries of such increases it would have taken the oceans to reach current salt levels from a hypothetical initial salt-free state, the maximum age of the Earth’s oceans can be accurately estimated.
Which of the following is an assumption on which the argument depends?

A. The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.
B. At any given time, all the Earth’s rivers have about the same salt levels.
C. There are salts that leach into the Earth’s oceans directly from the ocean floor.
D. There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.
E. None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans.表明海里的盐分是可以计算的，因为没有其他因素影响

谢谢了！

[此贴子已经被作者于2005-7-12 7:38:12编辑过]

携隐

本题已有三条讨论链接，请楼主再搜索一下。请注意搜索时要输入中文模式下的长杠而不是英文模式下的短杠。

泡泡老婆

明白了，谢谢斑竹

kathleen

偶也选(E),  为什么我搜索不到其他的讨论呢??