求助一道GWD的题Q13

yhwut · 发表于 2009-11-12 23:03:40

Q13

Lyme disease is caused by a baterium 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. Adeer 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.

答案是C，不理解为什么

genius_fang · 发表于 2009-11-13 22:07:09

文中说L疾病是由于dt在幼虫时期喂食了一种mice然后感染了一种细菌，然后传染给人类。但是，当喂食了其他的东西，dt就不会感染这种细菌，所以得出结论：如果其他喂食的种类数量大大增加，dt就会大大减少感染细菌，从而人类感染L疾病的机会也少。C指出，dt在幼虫期只会被喂养一次，加强了~因为如果只有一次机会，那么其他喂得东西多了，自然喂mice的机会少了，那么感染细菌的机会自然也少了~

yhwut · 发表于 2009-11-14 06:02:00

我的困惑是，其他species增多》dt的食物增多》dt繁殖的更多》weaken
难道此题还有隐含的assumption是dt的总数是不变的？怎样判断

genius_fang · 发表于 2009-11-15 23:00:44

我个人觉得，dt的食物增多》dt繁殖的更多这个推理是无法从原文得出的，谁说食物增多繁殖就要增多？？？这个LZ自己的题外联想~GMAT的逻辑推理都是步步紧扣的，只要原文不能直接推出，就不能作为推理结论！！！

jyw0411lsq · 发表于 2011-2-15 21:47:37

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求助一道GWD的题Q13

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