这题为何B不行？

frankzhiwei · 发表于 2010-9-30 17:22:43

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.

答案选A，可是B不也一个意思嘛，都是说起码保证过程中没有出现任何异常变化！跟A异曲同工之妙呀~
求解释~

sunshengkun666 · 发表于 2010-10-1 12:08:35

lz同志，鄙人愚昧见，b项的意思是在某一种给定的时间（点），所有河流的含盐量是一样的，而不是说在所有的时间里，河流的含盐量是不变的???

这题为何B不行？

所属分类: GMAT考试

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