问一道tricky新PREP 100

BreezyCipher · 发表于 2010-10-10 00:26:00

100. (30745-!-item-!-188;#058&005748) (T-9-Q28. ???-7-13 ,different type)

Lymedisease is caused by a bacterium transmitted to humans by deer ticks. Generally, deer ticks pick up the bacteriumwhile in the larval stage by feeding on infected white-footed mice. However, certain other species on which thelarvae feed do not harbor the bacterium. If the population of these other species were increased, more of the larvaewould be feeding on uninfected hosts, so the number of ticks acquiring thebacterium would likely decline.
Whichof the following would it be most important to ascertain in evaluating theargument?
A.Whether populations of the other species on which deer tick larvae feed arefound only in areas also inhabited by white-footed mice
B.Whether the size of the deer tick population is currently limited by theavailability of animals for the tick's larval stage to feed on
C.Whether the infected deer tick population could be controlled by increasing thenumber of animals that prey on white-footed mice
D.Whether deer ticks that were not infected as larvae can become infected asadults by feeding on deer on which infected deer ticks have fed
E.Whether the other species on which deer tick larvae feed harbor any otherbacteria that ticks transmit to humans

OA B
我个人比较同意的一个对B的解释
(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.

If the answer is yes, the size of the deer tick population is currently limited by the availability of food sources, then the conclusion is weakened - an increase in food sources would likely just lead to an increase in deer ticks, not a spreading out of deer ticks to these other animals.

If the answer is no, the size of the tick population isn't currently limited by the availablity of food sources, then the conclusion is strengthened - the same number of ticks spread out over more animals, a higher proportion of which are uninfected, means that fewer deer ticks will be exposed to the bacterium.

Note that neither answer proves or disproves the conclusion (e.g. we don't know for sure if deer ticks will spread out to other animals), but that's not our task - we just want the choice that's most relevant.
但是我还是无法排除D，很多讨论排除掉D理由都是irrelevance。例如下面两种解释
D.) There's no mention of deer in the paragraph, just deer ticks. Looks like another trap. Would be more enticing if it mentioned general other species instead of deer specifically.

(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.

Wuzzat? This might be relevant to the general issue about how ticks get infected, but we know nothing at all about the life cycle of the tick - as soon as we see "become infected as adults" we should eliminate this as outside the scope (especially because it has nothing to do with the food sources of larvae).
但是如果adults可以被感染的话，同样可以削弱文中的措施；只是如果不可以的话似乎不能加强结论。
如果一道题考虑这么多哪里做的完？
但是用相关性排除的话，偶第一个就把B排掉了

想问一下大家有什么好方法么？

BreezyCipher · 发表于 2010-10-10 23:33:02

我无奈的自己顶起来

BreezyCipher · 发表于 2010-10-12 15:04:57

我再顶…堂堂CD

网啊

Christianyang · 发表于 2010-10-14 14:57:49

那就帮顶吧

甜你一口 · 发表于 2010-11-19 22:37:55

如果adult会被感染也不会对文中的措施带来削弱，因为虽然在使用措施得情况下最终感染的数量上升了，但如果不用该措施最终感染数量也会上升了，两种情况的差异并没有缩小。

xpyin · 发表于 2012-2-4 09:42:44

试着回答下：
首先这题题干和选项都比较绕，先翻译下：
L这种病由鹿虱带的细菌传染给人。通常，鹿虱在幼虫阶段由于咬了被感染的白蹄老鼠才会感染这种细菌。但是，鹿虱幼虫叮咬的某种其他老鼠不带这种细菌。如果这些其他老鼠增加了，那么更多的鹿虱幼虫将叮咬没被感染的老鼠，那么感染细菌的鹿虱幼虫数目将减少。

结论是：其他不带菌老鼠增加，那么感染细菌鹿虱幼虫将减少。（答案必然有两者关系的内容）。
题型是评价题，评价题可以当作weaken 和support 题目来做，因为对它的Y或是N回答可以其他支持和反对的作用。

A. Whether populations of the other species on which deer tick larvae feed are found only in areas also inhabited by white-footed mice是否鹿虱叮咬的其他不带菌老鼠只在白蹄老鼠的被发现。不涉及两者关系，无关。
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是否鹿虱数量目前受限于鹿虱幼虫叮咬的宿主的数量。涉及两者关系。
如果回答N，那么鹿虱不受限叮咬寄主数量，引入新的宿主也无济于事啊。
如果回答Y，那么没有那些白蹄老鼠身上的鹿虱会Jump到新的寄主身上，减少感染。
C. Whether the infected deer tick population could be controlled by increasing the number of animals that prey on white-footed mice是否感染鹿虱数量可有通过增加白蹄老鼠的天敌来控制，不涉及两者关系。
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是否在幼虫结算被感染的鹿虱在成虫阶段由于叮咬了鹿而被感染，这些鹿是有被感染的鹿虱叮咬过。完全没关系啊。
E. Whether the other species on which deer tick larvae feed harbor any other bacteria that ticks transmit to humans是否鹿虱叮咬的其他老鼠带有其他细菌，会由鹿虱传染给人，更加没关系了。

另外，这题还有一道变体：
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 whitefooted 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.

OA is C

问一道tricky新PREP 100

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