请大家来看看这道有争议的逻辑题~GWD12 Q29~

yydetiankong

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.
我选的是B~看到以前的讨论里面大部分人选A还有人选E ~可是我怎么看都觉得A选项看不出个所以然来~
求解答~~~~~~~~thx~~~~`

睡着的鞋

答案应该是A。

over the past hundred years 是指过去的一百年。如果是过去几百年，应该为over the past hundreds of years。一个hundred有加“S”，一个没有。所以原文的resulting increase 是指过去一百年的盐分增加量，而不是简单的过去某个时间段的盐度增加量。


原文的主题意思：先算出过去一百年的盐度增加，再算出海洋从盐度为零到目前盐度需要花多少个世纪（一个世纪正好一百年）的这种增加量。

算法为：目前盐度/过去100年的盐度增加量=多少个世纪从零盐度到目前盐度。

该算法的假设：过去100年的盐度增加量可以当作速率，即每个100年的盐度增加量是一样的或低估了（因为低估，算出的时间比实际大）。

结论。这种算法可以精确算出海洋最大年龄

A。将A取非，则过去一百年的盐度增加量作为速率是高估了，则算出年龄比实际小。结论不成立，是not+weaken。故为答案

云游

If the dissolved water has become unusually large, then we can hardly get the expected data based on the formula—Years= dissolved amount/ increased salt level(during the past 100 years)* 100. In other words, if dissolved water is extremely large, say proximate to infinite, then the years we get will also be proximate to infinite. Therefore, the exact date can’t be accurately calculated.

This is a defender assumption, which helps eliminate a possibility that would weaken the arguement.