大全3－12 一道倒浆糊的题目

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

(E) monarchs communicate in intergenerationally via electromagnetic fields

我问了一个老美，那个人傻了八几的，开始选D，后来选C，后来我和他说是B，他很惊讶，然后说I think that each of the Monarchs should carry illegal Mexican immigrants with them back to Mexico City  开始谈论In USA they have a problem with many Mexican people illegaly crossing into USA, n USA we have a problem with many Mexican people illegaly crossing into USA,

然后我叫他FOCUS ON THIS QUESTION，

他说it doesn't matter that the monarchs arrive to Mexico City even though they have never been there, I don't think any of the migrating insects or birds remember - that would require more advanced brains.  The answer may have more to do with the sun, moon, seasonal cycles, etc.

我倒！！！

但是请教一下各位大虾到底答案和理由是什么

顺便说声美国人其实挺笨的

要证明是否对电磁场electromagnetic fields有感应

第一步：As a first step 要证明的是什么？

- 对电要有反应（放的是low-voltage transmitter 低压发射器）

记下来是第二步，第三步，......

如果选D的话，那就是“一步证明到位”（太不严谨了：））

If the butterflies are either especially attracted to the grove with the transmitter or especially repelled by it, 仔细感觉一下，B 比较合适。

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

方向有问题：C说的是“电对M的影响”

B说的是“M对电的敏锐感觉”

而假设的理论是：M根据电磁场maping，那么M必须对电磁场有敏感度，而证明电磁场对M有影响显的并不那么必要，即使是电对M有影响，电磁场不会主动使得M去画地图。而是M感觉到了电磁场的变化，才去画地图。

所以B更加准确一些。 这题太细微了，个人感觉。