prep上一题实在想不通急啊！！

meesh

Capuchin monkeys in Venezuela often rub a certain type ofmillipede into their fur.  Secretions ofthese millipedes have been shown to contain two chemicals that are potentmosquito repellents, and mosquitoes carry parasites that debilitate thecapuchins.  The rubbing behavior is rareexcept during the rainy season, when mosquito populations are at theirpeak.  Therefore, the monkeys probablyrub the millipedes into their fur because doing so helps protect them againstmosquitoes.

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

(A) Whether the two chemicals provide any protection forthe millipedes against their own predators

(B) Whether the type of millipede used by the capuchinmonkeys in Venezuela is found in other parts of the world

(C) Whether animals other than capuchins rub insects ofany kind into their fur

(D) Whether the only time the millipedes are readilyavailable to the capuchins is during the rainy season

(E)Whether secretions of any other insects accessible to the capuchins contain chemicalsthat repel mosquitoes

这题选d，我选了a。。题干中说“The rubbing behavior is rare except during the rainy season, when mosquito populations are at their peak.” 雨季的时候这种rubbing行为比非雨季时要多，雨季时蚊子也是最多的。感到不理解。。d选项，如果雨季是唯一能get the millipedes的季节为什么就一定能说明结论呢，反之，若是雨季并不是猴子们能get the millipedes的唯一季节（也就是一年四季都可能），那也有可能说明结论啊，因为非雨季时mosquito populations are not at their peak但并不代表就没有蚊子啊，可能只是蚊子比较少罢了所以rubbing的频率也就比较rare。。 这道题目感觉不知道它分析的点应该在哪里。。逻辑比较混乱。。求nn看过来！！～

xiqiong

我们先来理清思路：说monkey 的rubbing behavior 在雨季时多，所以monkey 做rubbing事为了驱逐蚊子。
这是我们需要抓住的。就是：因为雨季rubbling多，所以行为是驱蚊。
如何evaluate就是看因果关系是否成立：
A，说什么chemical，和逻辑链没关系。
D，是否millipede只在雨季有。也就是monkey是否有其它限制呢？即能rubbling的条件是有millipede，但millipede只雨季有。这就导致因果关系受阻。
只要抓住逻辑链，去分析就好。不要被其它信息干扰^_^
ps：evaluate是支持或削弱结论。不能用取非看。

meesh

xiqiong 发表于 2013-8-18 17:41
我们先来理清思路：说monkey 的rubbing behavior 在雨季时多，所以monkey 做rubbing事为了驱逐蚊子。
这是 ...

谢谢！学到了！！～