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题库 / OG2016-RC-44
A small number of the forest species of lepidoptera (moths and butterflies, which exist as caterpillars during most of their life cycle) exhibit regularly recurring patterns of population growth and decline—such fluctuations in population are known as population cycles. Although many different variables influence population levels, a regular pattern such as a population cycle seems to imply a dominant, driving force. Identification of that driving force, however, has proved surprisingly elusive despite considerable research. The common approach of studying causes of population cycles by measuring the mortality caused by different agents, such as predatory birds or parasites, has been unproductive in the case of lepidoptera. Moreover, population ecologists' attempts to alter cycles by changing the caterpillars' habitat and by reducing caterpillar populations have not succeeded. In short, the evidence implies that these insect populations, if not self-regulating, may at least be regulated by an agent more intimately connected with the insect than are predatory birds or parasites.
Recent work suggests that this agent may be a virus. For many years, viral disease had been reported in declining populations of caterpillars, but population ecologists had usually considered viral disease to have contributed to the decline once it was underway rather than to have initiated it. The recent work has been made possible by new techniques of molecular biology that allow viral DNA to be detected at low concentrations in the environment. Nuclear polyhedrosis viruses are hypothesized to be the driving force behind population cycles in lepidoptera in part because the viruses themselves follow an infectious cycle in which, if protected from direct sunlight, they may remain virulent for many years in the environment, embedded in durable crystals of polyhedrin protein. Once ingested by a caterpillar, the crystals dissolve, releasing the virus to infect the insect's cells. Late in the course of the infection, millions of new virus particles are formed and enclosed in polyhedrin crystals. These crystals reenter the environment after the insect dies and decomposes, thus becoming available to infect other caterpillars.
One of the attractions of this hypothesis is its broad applicability. Remarkably, despite significant differences in habitat and behavior, many species of lepidoptera have population cycles of similar length, between eight and 11 years. Nuclear polyhedrosis viral infection is one factor these disparate species share.
Which of the following, if true, would most weaken the author's conclusion in the highlighted text?
New research reveals that the number of species of birds and parasites that prey on lepidoptera has dropped significantly in recent years.
New experiments in which the habitats of lepidoptera are altered in previously untried ways result in the shortening of lepidoptera population cycles.
Recent experiments have revealed that the nuclear polyhedrosis virus is present in a number of predators and parasites of lepidoptera.
Differences among the habitats of lepidoptera species make it difficult to assess the effects of weather on lepidoptera population cycles.
Viral disease is typically observed in a large proportion of the lepidoptera population.
题目分析：
文章推断题：以下哪个可以削弱作者在line 18-22的结论？
原文：总而言之，这些证据表明，如果不是自我调节，一定有个和昆虫更亲密的东西在调节
这个结论的证据是：“鸟和寄生虫”的办法不适用；通过改变栖息地和减少毛毛虫数量的办法也失败了。
本题逻辑链：因为X不是原因，Y不是原因，所以猜测是Z是原因。正确选项：现在新发现X可以是原因，削弱原结论。
选项分析：
A选项：新研究表明，吃L的鸟和寄生虫的数量这几年明显下降：他们的数量对办法有没有用并没有影响，即使数量减少也不能改变“不适用”这个结果。
B选项：正确。新实验（用新办法改变栖息地）成功缩短了L的population cycle：说明之前的办法不全面，现在有了新办法且成功了，说明driving force很有可能并不是另一个agent。
C选项：最近的实验发现病毒在L的捕食者和寄生虫里：说明病毒和population cycle的关联度更高了，加强了结论。
D选项：L物种的栖息地不同，导致很难估计天气的影响：天气的影响难以估计≠天气对栖息地有影响，从而进一步对population cycle有影响。
E选项：很大一部分的L有病毒存在：病毒存在越多，越可以加强结论。
研究者发现：1想要探寻改变life circle的因素（这是研究的目的，要搞清楚）； 2）通过改变habitats，或者减少了毛毛虫的数量的办法 change life cycle； 两者都没有成功（排除法）
conclusion:这些虫子如果不是自我调节，就一定有个和昆虫更亲密的东西在调节life circle
A选项：新研究表明，吃L的鸟和寄生虫的数量这几年明显下降：他们的数量对办法有没有用并没有影响，即使数量减少也不能改变“不适用”这个结果。（顶多说明鸟和寄生虫的影响有限，无法削弱结论！）
B选项：正确。新实验（用新办法改变栖息地）成功缩短了L的population cycle：说明之前的办法不全面，现在有了新办法且成功了，说明driving force很有可能并不是另一个agent。（新方式改变栖息地是为它因！）
population cycle 肯定和agent 有关，削弱：和agent 无关
rc
b引入他因；
且他因是前面premise的否定，这在rc中的逻辑分析是可以且常见的。直接否定了“opulation ecologists' attempts to alter cycles by changing the caterpillars' habitat but failed”
说了“New experiments in which the habitats of lepidoptera are altered（ in previously untried ways） result in the shortening of lepidoptera population cycles.”
因为研究者发现：1）测量由鸟类等捕食者造成的死亡率 ； 2）通过改变habitats，或者减少了毛毛虫的数量的办法 change life cycle； 两者都没有成功
conclusion:这些虫子如果不是自我调节，就是由一个和昆虫有紧密关系的东西所调节的
C选项说病毒存在于病毒存在于一些捕食者的体内，加强了病毒和昆虫的联系
哦，这个题一开始想复杂了，其实病毒在捕食者里面发现证明了这个事情就是病毒干的。。。一开始想成病毒通过捕食者干预。。。忘了这是捕食者不是它的食物
原句的逻辑，不是A理由，那就是B理由
B选项的逻辑：还有C理由可以解释（正确选项）
C选项：B理由实际可以涵盖A理由（错误）
本文需要削弱：如果不是自我调节的话，就被与此昆虫紧密相关物体，而不是鸟或寄生虫所调节。削弱它所支持的：只要找出－被鸟或寄生虫调节；或其它调节，例如habitats或是减少的人口。
A选项：无关
B选项：habitats有关
C选项：nuclear polyhedrosis virus不属于parasites of lepidoptera， 而是 an agent more intimately connected with the insect
D选项：无关
E选项：加强－病毒疾病an agent more intimately connected with the insect
错选c，加强了结论。
Moreover, population ecologists' attempts to alter cycles by changing the caterpillars' habitat and by reducing caterpillar populations have not succeeded。答案从这句中来。作者通过陈述两件事来说明caterpillar的population cycle与自身关系更大而与环境或者天敌无关。一，天敌population cycle与 lepidoptera 的population cycle不相关；二，改变caterpillars的栖息地不能改变population cycle. 所以b削弱二自然是削弱来作者的结论。
A 天敌显著下降，无关
C加强
D跟天气影响无关
E并不能削弱结论
C选项属于加强
highlight说的是 虫的数量是被更亲密的媒介所控制，而不是被鸟和寄生虫。
B 这个虫的栖息地改变了，导致虫的数量变少了。显然栖息地并不是更亲密的媒介，属于第三因素，削弱作者观点
C 首先这个nuclear polyhedrosis virus是在后文被提及的，和highlight内容还没有建立关系，其次，vrius是更亲密的媒介，这里属于加强
D 中关注的栖息地和天气都不属于更亲密的媒介
E 同理C
B Correct. Newexperiments involving changesinhabitat that didsucceedin alteringpopulation cycles would suggest that the populations are not in fact self regulating, and that the search for another cycle-alteringagent maybeunnecessary.
C是加强。。。（简直无法理解自己怎么错的这道题）
但是d为什么不对啊 忽略了天气的影响 说天气也有可能是原因之一啊
OG上的解释是，D天气影响难以测量不代表它对虫的数量就有影响。
但是B中点明了栖息地改变对虫的数量有影响。
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habitats of lepidoptera are altered in previously untried ways result in the shortening of lepidoptera population cycles.选项b说在没有尝试过的方法中，习惯的转变导致了数量的缩减。和原文中说的通过转变习惯没有成功相反，也就是驳斥了。alter cycles by changing the caterpillars' habitat and by reducing caterpillar populations have not succeeded.
habitat 是栖息地不是习惯。我开始也做错了。但是第二遍认真思考了下。最后的conclusion：In short, the evidence implies that these insect populations, if not self-regulating, may at least be regulated by an agent more intimately connected with the insect than are predatory birds or parasites.前面说过研究predatory birds or parasites这些agents,但都不是。这里再次强调是比predatory birds or parasites更加紧密的agent造成的。这题是削弱题，只要找一个答案不是agent造成的就可以。而用之前没有试过的方式改变栖息地habitat，结果改变了cycle, 就跟agent没有关系啦。所以选这个。 请老师指正。
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这些insect population的变化，如果不是自身原因，则可能是和insect关系更加密切的agent相关，与鸟和寄生虫之类相比。
削弱结论，则insect population和这个agent可能没有什么关系，B说明了insect数量减少的另外一个原因，就是生存环境的变化
属于果因推理的说明结果问题，提出了另外一个事件引起了insect数量减少
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