GWD 6-13

kaki3193_cn

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 bacteria for many tick larvae.
E.None of the other species on which deer tick larvae feed harbor other bacteria that ticks transmit to humans.
为什么选C呢?不明白

[此贴子已经被作者于2006-12-4 17:49:28编辑过]

vincentwh

其实该题单纯从有关无关就可以找到答案C

原文推理是：1。T传细菌给人类，人类感染L病。2。T在幼虫是吃M就带该细菌。3。幼虫吃其它东西不带该细菌。所以（结论），其他东西多拉，携带该细菌的T就少，人类感染L病的机会也少。

A。无关。T携带该细菌是否有反作用和结论无关

B。无关。主要有两个因素决定和结论无关。1是原文讨论的是T传细菌给人类导致人类得L病，人类直接接触M 是否得L病与原文无关。2是知不知道有没有这样的CASE并不代表实际有没有，所以对原文不起作用。

C。支持。T 在幼虫期只是进吃一次。既然只吃一次，这次不是吃M就是吃其他东西，当其他东西变多时，吃M的机率就变少，所以T感染该细菌就少。支持结论

DE都无关。

gmat30

thanks