GWD16-29,GWD20-28,GWD26-29

GWD16-29:
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.

答案是E，我觉得E也是对的，因为如果已经流入海里的盐份被海洋生物消耗了一部分，那么自然无法测量刚流入海洋那会儿的盐份有多少了。
但是A为什么错呢，我觉得也有道理啊，因为如果过去几百年里可能存在超常的盐份流入，测量出来的实际盐份会比正常状态下多，会高估地球的年龄。
另外，选项B中，虽然有点太绝对了，肯定错，但是反过来想想，是不是这道题中只有两种情况会影响地球年龄测量，第一就是最初流入海中盐份的测量错误，E选项中出现的海洋生物消耗盐份就会导致这种情况，第二就是最初流入海中盐份测量没错误的情况下，由于过去每年流入海洋的盐份差别较大，无法准确算出地球的年龄。
因此，我觉得这道题AE都对，B选项如果将at any give time去掉，换一种语气的话也对。

GWD20-28:
Historian:  In the Drindian Empire, censuses were conducted annually to determine the population of each village.  Village census records for the last half of the 1600’s are remarkably complete.  This very completeness makes one point stand out; in five different years, villages overwhelmingly reported significant population declines.  Tellingly, each of those five years immediately followed an increase in a certain Drindian tax.  This tax, which was assessed on villages, was computed by the central government using the annual census figures.  Obviously, whenever the tax went up, villages had an especially powerful economic incentive to minimize the number of people they recorded; and concealing the size of a village’s population from government census takers would have been easy.  Therefore, it is reasonable to think that the reported declines did not happen.In the historian’s argument, the two portions in oldface play which of the following roles?

A. The first supplies a context for the historian’s argument; the second acknowledges a consideration that has been used to argue against the position the historian seeks to establish.
B. The first presents evidence to support the position that the historian seeks to establish; the second acknowledges a consideration that has been used to argue against that position.
C. The first provides a context for certain evidence that supports the position that the historian seeks to establish; the second is that position.
D. The first is a position for which the historian argues; the second is an assumption that serves as the basis of that argument.
E. The first is an assumption that the historian explicitly makes in arguing for a certain position; the second acknowledges a consideration that calls that assumption into question.

同样一道题，GWD20的答案是C，GWD7的答案是D，到底是哪个啊？

GWD26-29
Educational Theorist: Recent editorials have called for limits on the amount of homework assigned to children. They point out that free-time activities play an important role in childhood development and that large amounts of
homework reduce children’s free time, hindering their development. But the average homework time for a ten year old, for example, is little more than 30 minutes per night. Clearly, therefore, there is no need to impose the
limits these editorials are calling for.

Which of the following is an assumption on which the educational theorist’s argument relies?
A. The free-time activities that ten year olds engage in most are all approximately equally effective at fostering development
B. Regularly doing homework assignments improves children’s academic performance.
C. Individual teachers are not the best judges of how much homework to assign the children they teach
D. In most schools, if not all, the homework assignments given are of a length that does not diverge widely from the average.
E. Free-time activities rarely teach children skills or information that they can use in their academic work.

不明白为什么选D，我选了B？？

GWD16-29:

是这样的，那个生物，是有机活体，消耗盐不假，但在有限的时间内，会进行新陈代谢，生物多样性会保持大自然各种物质的生态平衡，生物死了也会降解，取之于海洋，还之于海洋，used up 是永远不会发生的。

选A

GWD20-28:C

GWD26-29：

结论讲到the average homework time，答案需要进一步解释

B无关

噢，这样啊，多谢LS的回答

题目是要求选一个assumption，所以不用考察这些选项本身的正确还是错误，而是将这些选项都看成是正确的。

你是将E选项这个假设前提做了一个客观的解释，似乎超出了试题考察的范围了。不足以否定E

欢迎讨论

首先我是基于used up ，GMAT的正确选项从来不用这种词

第二，这个考试经常需要用基本常识做出理性的判断，不光这道题