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标题: GWD-TN-20-32 [打印本页]

作者: wynyy2000    时间: 2011-5-13 14:08
标题: GWD-TN-20-32
A major chemical spill occurred five years ago at Baker’s Beach, the world’s sole nesting ground for Merrick sea turtles, and prevented nearly all the eggs laid that year from hatching.  Yet the number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago. Clearly, environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded.

Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists’ prediction?

A.The chemical spill five years ago occurred at a time when there were neither Merrick sea turtles nor Merrick sea turtle eggs on Baker’s Beach.
B.Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old  
C.Under normal conditions, only a small proportion of hatchling female Merrick sea turtles survive in the ocean until adulthood and return to lay their eggs at Baker’s Beach.
D.Environmental pressures unrelated to the chemical spill have caused a significant decline in the population of one of the several species of sea birds that prey on Merrick sea turtle eggs
E.After the chemical spill, an environmental group rejected a proposal to increase the Merrick sea turtle population by transferring eggs from Baker’s Beach to nearby beaches that had not been affected by the spill. Transfer of eggs is irrelevant  
本题选B,求解释,我对B的感觉是半懂不懂的

作者: kikisunflower    时间: 2011-5-13 14:54
现象1:5年前BB海滩被污染,且污染阻碍那一年海龟蛋的孵化→那一年海龟的population下降→现象1支持的是环境学家的观点,即污染减少了海龟数量

现象2:但污染后,来BB海滩产卵的母龟增加→作者认为母龟的增加可以说明污染没有减少海龟数量

B指出:这些母龟大量出现的时间在污染之前(因为这些母龟是10年前出生的,它们那会儿还没污染,所以它们的数量有多少,根本不管污染的事,只能反映10年前的海龟数量情况;要是想知道这个污染对海龟数量的影响,至少得看5年后来BB海滩下蛋的海龟数量)→反驳了作者的观点




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