请教GWD6-21，7-19

GWD6-21:
Scientists have made genetic modifications to cotton to increase its resistance to insect pests.  According to farmers’ report, the amount of insecticide needed per acre to control insect pests was only slightly lower for those who tried the modified seed than for those who did not.  Therefore, since the modified seed costs more than ordinary seed without producing yields of higher market value, switching to the modified seed would be unlikely to benefit most cotton armers economically.

Which of the following would it be most useful to know in order to evaluate the argument?

A. Whether farmers who tried the modified cotton seed had ever tried growing other crops from genetically modified seed
B. Whether the insecticides typically used on ordinary cotton tend to be more expensive than insecticides typically used on other crops
C. Whether for most farmers who grow cotton it is their primary crop
D. Whether the farmers who have tried the modified seed planted as many acres of cotton, on average, as farmers using the ordinary seed did
E. Whether most of the farmers who tried the modified seed did so because they had previously had to use exceptionally large quantities of insecticide
答案是D

A显然不对，不涉及other crops，无关
B假如B成立，那么由于种ordinary cotton不但产量少，而且所耗费的insecticides的成本也高，自然就不如种modified seed了。假如B不成立，虽然ordinary cotton产量少，但是所耗费的insecticides成本，所以和modified seed就没法比，有削弱性。
C无关
D 假如成立，那么说明利用两种seed种cotton的样本量是一样的，这就消除了因为两者种植量不同而造成差异的可能性，strengthen了结论，比如modified seed种100亩，而ordinary只种1亩，显然可能存在随机的误差，让ordinary不具有代表性。假如不成立，就不能消除这种差异的可能性，有削弱性。
E 如果E成立，只能说明由于之前farmers种的ordinary需要异常多的insecticide，所以想试试新的modified seed，但是并不能说明试出的结果一定就是好的。如果E不成立，那就更不能说明任何问题了。
所以，争论在B选项和D选项之间，大家看看应该如何？

GWD7-19:
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 knowledges a consideration that calls that assumption into question.

答案选D，但是the second我怎么觉得就是根据前面推理出的这个题目的

conclusion不是assumption啊，如果这个真的不是conclusion那是哪个啊

GWD6-21:

D是否农民种了相同面积，与原文所说农药用量相距太远 ，无关

选B

GWD7-19:

第一句明显是背景，第二句明显是结论

C

GWD6-21: D

A.C无关，排除

B.E可以结合看，要价格贵和量大，那么即使撒农药的量slightly lower，也strengthen了结论，否则就weaken了结论，那么单独看价格或者量大，就无法判定是加强还是削弱了

D：农民报告说农药量slightly lower，要看他是在多大的种植面积上得出的结论，如果他种植的基因种棉花面积很小，那么这个slightly lower误差会很大，就无法否定基因种子的价值了，如果他种植的面积很大，那么这个slightly lower就比较可靠，那么就说明基因种子没什么价值，strengthen了结论

楼上这位仁兄请了：

我觉你对D选项作出了过多的解释，比如：“棉花面积很小”再比如：“这个slightly lower误差会很大”

D选项中只说"种植面积是否相同"，很多、很小、很大都是个人的无限推理，那是无穷无限的。

是否相同的意思是：相同或不相同

相同都否定结论吗？

不相同能支持结论吗？

突然发现自己把两道一样的题目放在不同的帖子里了，s7s7兄弟还是都回答了，非常感谢哈！

GWD6-21题现在看来似乎B选项对于原题的作用要比D选项更加直接一点

先说这个argument的conclusion：modified seed would be unlikely to benefit most cotton (f?)armers economically

就是基因种子与普通种子相比不能给农民带来经济效益

D：“种植面积是否相同？”如果基因种子的种植面积小，可能会因为种植面积小而没有体现出经济效益，所以weaken结论；如果种植面积相同，或者更大，那么不会因为种植面积上的原因而影响经济效益，strengthen结论

再看B：“棉花上撒的农药是否比别的作物贵？”影响棉花经济效益的有两个方面，一个是农药的花费，一个是种子的价格（文中说了基因种子价格更贵）。农民说农药是使用量是slightly lower，如果这个lower的量乘以农药的价格，不足以抵消种子价格的上涨，那么strengthen结论，反之weaken，所以与农药价格比别的作物贵无关

好的，我就按照楼上的思路推：

如果面积不同，会有两种情况：

支持结论；削弱结论

好

面积不同就能推出两种不同结论，这一点足以说明：D是错的

那“面积相同”呢？

D选项中只说"面积是否相同"，什么“大”“小”“多”“少”都是楼上想出来，D选项没说。

我也来发表一下谬论，我觉得选E

A无关排除，other crops

B无关排除，other crops

C无关排除，primarily

D以实验亩数越多，误差越小的角度说，D好像靠谱，但是却不能说明原题中的结论就一定是错误的；

E参加实验的人是否原来需要使用大量的杀虫剂呢？如果是，那么由于基因种子没有达到他们预期的增加收益的效果，那么就support了结论；相反，如果否，也就是说他们原来的cotton就不需要太多杀虫剂，那么即便用了基因种子，也不会有明显的效果，不能证明基因种子就没用，那么就weaken了结论。