天山-7-13

Q13:

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.

终于懂了，谢谢！

答案是C.

我还是不太懂呀….可不可稍稍用中文讲解一下

C是支持，我理解是如果只吃一次，而没有细菌的species增多的话，ticks通过吃而沾染上细菌的概率就会变小，从而支持了结论）。

可是怎么感觉B是一个assumption啊？

结论说：如果ticks吃的没有细菌的species增多，那么会沾染上细菌的ticks数量会减少，从而人类感染这种疾病的数量也会减少。

B说人类不会直接从携带细菌的mice那里被传染上该疾病。（取非的话就削弱了结论吧。取非就是说就算species增多，携带细菌的ticks数量增多，感染该疾病的人类的数量也不一定会减少，因为可以从mice那里直接传染过来。）

assumption也是支持的一种啊。

请指教B错误在哪里啊？（我有点感觉B只是削弱了结论中间小部分，结论是从species增多得到的，而B却和这个没有关系，C更贴近题目。但是B取非也确实是削弱了结论啊。