｛1｝Which of the following, if true, wouldmost weaken the author’s conclusion in lines 25-30?
A.New research reveals that the numberof species of birds and parasites that prey on lepidoptera hasdroppedsignificantly in recent years.
B.New experiments in which the habitatsoflepidoptera are altered in previously untried ways result in the shorteningoflepidoptera population cycles.
C.Recent experiments have revealed thatthe nuclear polyhedrosis virus is present in a number of predators andparasites of lepidoptera.
D. Differences among the habitatsoflepidoptera species make it difficult to assess the effects of weatheronlepidoptera population cycles.
E. Viral disease is typicallyobservedin a large proportion of the lepidoptera population.
｛2｝It can be inferred from the passage that the mortality caused by agents such aspredatory birds or parasites was measured in an attempt to
A.develop an explanation for the existenceof lepidoptera population cycles
B.identify behavioral factors in lepidoptera thataffect survival rates
C.identify possible methods for controlling lepidoptera population growth
D. provide evidence that Lepidoptera populationsare self-regulating
E. determine the life stages oflepidoptera at which mortality rates are highest
（3）The primarypurpose of the passage is to
A.describe the development of newtechniquesthat may help to determine the driving force behind population cyclesin Lepidoptera
B. present evidencethat refutes a particular theory about the driving force behind populationcycles inLepidoptera
C.present a hypothesis about the drivingforce behind population cycles in Lepidoptera
D.describe the fluctuating patterns ofpopulationcycles in Lepidoptera
E. question the idea that a single driving forceis behind population cycles in Lepidoptera
这题选C吧。。。
（4）According to thepassage, before the discovery of new techniques for detecting viral DNA,population ecologists believed that viral diseases
A.were not widely prevalent among insectpopulations generally
B.affected only the caterpillar life stage of lepidoptera
C.were the driving force behind lepidopterapopulation cycles
D.attacked already declining caterpillar populations
E. infected birds and parasites that prey on variousspecies of lepidoptera
原文“but population ecologists had usuallyconsidered viral disease to have contributed to the decline once it wasunderway rather than to have initiated it.” | 
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发表于 2010-10-24 20:11:39
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