【实战方法】GMAT逻辑解题方法 by lawyer

lawyer_1

方法只是工具，找到答案，明白各类题的本质才是目的，其实明白各类题的本质，不管什麽办法，道理都相通的。拘泥于某种办法，无异于刻舟求剑。这就是为何作LSAT题有助于GMAT题的原因。因为它们的题的思路本质是一样的。明白了WEAKEN题的本质，LSAT题也好，GRE题也好，GMAT题也好，只要都是WEAKEN题，本质都一样，道理都相同。

lawyer_1

下面的连接的题很好的体现了结论的特殊性和具体性。

http://forum.chasedream.com/dispbbs.asp?boardid=24&id=172778&star=2#1630005

lawyer_1

条件型结论：结论带条件（即为充分必要）。WEAKEN的方法显示充分条件成立，必要条件可以不成立。或举反例，或提供有关信息。
条件型结论应该是结论为IF....THEN。因为这种题型很容易找到答案，所以特别列出。
毛毛同学的OG12CR分类中提到这类型OG12CR中的22题（毛毛的总结），列于此
22. In the arid land along the Colorado River, use of the river's water supply is strictly controlled: farms along the river each have a limited allocation that they are allowed to use for irrigation. But the trees that grow in narrow strips along the river's banks also use its
water. Clearly, therefore, if farmers were to remove those trees, more water would be available for crop irrigation.
Which of the following , if true, most seriously weakens the argument?
(A)  The trees along the river's banks shelter it from the sun and wind , thereby greatly reducing the amount of water lost through evaporation .
(8)  Owners of farms along the river will probably not undertake the expense of cutting down trees along the banks unless they are granted a greater allocation of water in return .
(C)  Many of the tree species currently found along the river's banks are specifically adapted to growing in places where tree roots remain constantly wet.
(0)  The strip of land where trees grow along the river's banks would not be suitable for growing crops if the trees were removed.
(E)  The distribution of water allocations for irrigation is intended to prevent farms farther upstream from using water needed by farms farther downstream.

本文结论：如果去掉树，可以多出水用于灌溉。
A. 去掉树（充分条件），也没有多出水用于灌溉（必要条件可以不成立）。因为虽然多出用于树的部分，去少掉蒸发部分。结果可能是反而更少水用于灌溉。