再问 TT GWD6-13

不好意思又起一新贴问 TT GWD6-13.  之前跟贴在别人后边, 但没人回应......

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?

1. Ticks
        do not suffer any adverse consequences from carrying the bacterium that
        causes Lyme disease in humans.
2. There
        are no known cases of a human’s contracting Lyme disease through contact
        with white-footed mice.
3. A deer
        tick feeds only once while in the larval stage.
4. A
        single host animal can be the source of bacteria for many tick larvae.
5. None
        of the other species on which deer tick larvae feed harbor other bacteria
        that ticks transmit to humans.

But  if people may  possibly contract Lyme disease from other sources  other than deer ticks,  No inforamtion listed in the argument disscussed such situation.

B:[ human’s contracting Lyme disease through contact with white-footed mice]is not discussed in the argument,and instead ,[Lyme disease is caused by a bacterium transmitted to humans by deer ticks]Only one factor is discussed.That is deer ticks transmitted Lyme disease to humans.

其实整个文章是的前提是:

(1)人和鹿接触感染Lyme

（2）鹿感染导致Lyme的细菌是在larval stage吃了infected white-footed mice

（3）其他动物也吃infected white-footed mice

结论：

其他动物增加 －》人感染lyme减少

B是说人感染lyme是通过infected white-footed mice （其实与结论无关，其他动物增加而人感染减少起不到任何加强作用）

C实说鹿只能在larvalstage才能被感染。

（说明鹿感染的时间很短，而其他动物增加，导致鹿在这段时间吃到white-footed mice机会更少所以加强。想想如果鹿在整个生命周期都会被感染，感染的机会就会增加，人被感染的机会也会增加，所以这里是加强）

楼上的理解有误。

题目说， 鹿虱传染Lyme给你。 鹿虱在幼虫时期吃infected 白脚老鼠感染病菌。 因为鹿虱幼虫们也吃别的玩意， 所以如果增加别的玩意的数量的话, 鹿虱们感染的机会就会比较下。

问什么选项加强。 要加强的是增加别的玩意的数量。

C说 鹿虱们幼虫时期只吃一顿， 如果有只有白脚老鼠， 那就要感染了。 如果有大量其他东西可以吃， 鹿虱们吃到白脚老鼠的机会就大大减少。 因为他们只吃一次！ 所以人类感染的可能也小。

B说没有人从和白脚老鼠的直接接触中感染。 这个不能加强为什么要增加别的玩意。

俺觉得楼上说的有些疑问。

原文的fact是：

1。deer tick 传染lyme

2.deer tick小时候吃mice,mice带lyme

3.其他的生物也带lyme

结论：其它生物增加了，lyme就减少了。

如果要strengthen的话,会有这么几个方向： deer tick 只能在mice上感染lyme(这里有一个假设，即deer tick总量不变，而且是equally likely to feed on its pray)，因为mice在总群的比例减小，所以deer tick感染lyme的机会就小了.我觉得题目缺了一个假设，大家觉得呢？

b说的是，人类不从mice上面感染lyme.显然这个说法和推理关系不大。如果说人类从。。。，可以weaken