大全-C-12

12.   Which of the following best completes the passage below?

Monarch butterflies, whose average life span is nine months, migrate from the midwestern United States to selected forests outside Mexico City. It takes at least three generations of monarchs to make the journey, so the great-great-grandchildren who finally arrive in the Mexican forests have never been there before. Yet they return to the same trees their forebears left. Scientists theorize that monarchs, like homing pigeons, map their routes according to the earth’s electromagnetic fields. As a first step in testing this theory, lepidopterists plan to install a low-voltage transmitter inside one grove of “butterfly trees” in the Mexican forests. If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, lepidopterists will have evidence that______

(A) monarch butterflies have brains, however minuscule

(B) monarch butterflies are sensitive to electricity

(C) low-voltage electricity can affect butterflies, whether positively or adversely

(D) monarchs map their routes according to the earth’s electromagnetic fields（B）

(E) monarchs communicate in intergenerationally via electromagnetic fields

1，为什么选B，而不是C。

2，low-voltage transmitter 和电流有关系吗？transmitter只能发射电磁波，而不是电流。

   说点个人看法：C没有一个正确答案应该具有的东西

   比如：1。butterflies和monarch butterflies ，那是两个意思，C明显可以理解为影响全部蝴蝶

2。whether positively or adversely错，什么叫positively什么叫adversely？？原文只说attracted 或者是repelled。

    逻辑在GMAT中叫critical reasoning，按我的理解就是：批评性推理，用批判的思维剔除选项。比如这个题目，在排除一个选项的时候，就反问一下自己：你怎么知道是这样的？？（批判性思维）这个题目的每个错误选项都可以通过这样的反问来排除。如果在削弱题中，就反问：这个就一定会导致。。。吗？？等等

     只是一点个人看法

我也觉得应该是受电磁影响，有点变扭，不过我不是太明白电什么的，但是B和C在这方面都是一样的，都用的是electricity。C的问题是不是它少写了Monarch？

谢谢谢谢！这一题的意思还有点不明白，但怎么解题很清楚了。

多谢二位NN！

解释合理!!!

再问一下，为什么不是Ｄ呢？是不是被我推理过头了？

 I couldn't agree any more. The range of butterflies is much bigger than that of monarch butterflies...that's the very flaw in choice C.