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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 by feeding on infected white-footed mice. However, certain other species on which the larvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvae would be feeding on uninfected hosts, so the number of ticks acquiring the bacterium would likely decline.
Which of the following would it be most important to ascertain in evaluating the argument? 目的：找到gap。评价题
背景：lyme disease 是由deer ticks体内的细菌引起的。Deer tick是在幼虫时期因为寄生在感染的白脚鼠所以才有体内的细菌。那些寄生在未感染物种的tick在幼虫时期没有染上这个细菌。
dt总量 = 吃不带细菌的宿主的dt的比例＊dt总量 + 吃带细菌的宿主的的比例＊dt总量
题目的逻辑链：提高不带细菌的宿主的数量－更多的dt选择寄生在这些不带细菌的宿主身上－ 携带细菌的dt数量下降
gap：吃不带细菌的宿主的dt的比例上升 吃带细菌的宿主的的数量下降 成立吗？需要dt总量不变才成立。
A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice
其他物种和白脚鼠之间的信息，无关。杀。
B. Whether the size of the deer tick population is currently limited by the availability of animals for the tick's larval stage to feed on
是否dt的总数能被 扁虱幼虫时期寄生对象的可得性 限制住。 即dt总量保持不变。这个复合猜想的gap，成立。
C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice
是否感染的扁虱的数量能被逐渐增多的捕食白脚鼠的物种数量控制。？？？为什么不对？
题目里问的是infected dt 的数量能否从m途径改变；c选项说的是n途径能改变infected dt的数量。N途径对m途径无影响。杀
（e.g. 做出租车会迟到吗？ C说啊哈做地铁不会迟到哦。 这事两个手段，干扰项。不能选）
D. Whether deer ticks that were not infected as larvae can become infected as adults by feeding on deer on which infected deer ticks have fed
是否那些幼虫时期没有感染的扁虱成年后会被感染，因为它们吃了那些感染的扁虱接触过的鹿，会变异成感染的扁虱。这个现象在人为提高不带细菌的宿主之前之后都是静态不变的。纵然确实会使扁虱变异，之前这种现象也是存在的。所以无所谓。杀
E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans
其他细菌，无关。杀
终于想通了，希望能帮助到你们！
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发表于 2016-6-24 17:42:07
