求T-9-Q28. 天山-7-13解释、

aary431

Lyme disease is caused by a bacterium transmitted to humans by deer ticks. Generally deer ticks pick up the bacterium while in the larval stage from feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. Therefore, if the population of these other species were increased, the number of ticks acquiring the bacterium and hence the number of people contracting Lyme disease would likely decline.

Which of the following, if true, most strengthens the argument?

A.Ticks do not suffer any adverse consequences from carrying the bacterium that causes Lyme disease in humans.

B.There are no known cases of a human’s contracting Lyme disease through contact with white-footed mice.

C.A deer tick feeds only once while in the larval stage.

D.A single host animal can be the source of bacterium for many tick larvae.

E.None of the other species on which deer tick larvae feed harbor other bacteria that ticks transmit to humans

答案C我能想通的，但为什么B不对啊？NN们行动起来啊、

wangsiwei

白脚老鼠只是题目给的一个背景资料。文章的中心是－－如果增加other species来和deer ticks争吃的，就会减少人类传染的概率。 关键就是为什么别的咚咚增加，deer ticks会减少传染的概率。不知道说明白了没有。

aary431

有点意思了、THX

shirleyon

白脚老鼠只是题目给的一个背景资料。文章的中心是－－如果增加other species来和deer ticks争吃的，就会减少人类传染的概率。 关键就是为什么别的咚咚增加，deer ticks会减少传染的概率。不知道说明白了没有。

-- by 会员 wangsiwei (2010/7/23 12:37:06)

不是other species来和deer ticks争吃的，而是deer ticks 会吃other species，而少吃或者不吃白脚鼠，从而降低传染病概率

可以参考这个帖子http://forum.chasedream.com/GMAT_CR/thread-453652-1-1.html?postid=14040103&searchmode=TopicContent&searchtext=lyme%20disease%20deer%20ticks