题目如下： Some species of Arctic birds are threatened by recent sharp increases in the population of snow geese, which breed in the Arctic and are displacing birds of less vigorous species. Although snow geese are a popular quarry for hunters in the southern regions where they winter, the hunting season ends if and when hunting has reduced the population by five percent, according to official estimates. Clearly, dropping this restriction would allow the other species to recover.
Which of the following, if true, most seriously undermines the argument?
A. Hunting limits for snow geese were imposed many years ago in response to a sharp decline in the population of snow geese. B. It has been many years since the restriction led to the hunting season for snow geese being closed earlier than the scheduled date. C. The number of snow geese taken by hunters each year has grown every year for several years. D. As their population has increased, snow geese have recolonized wintering grounds that they had not used for several seasons. E. In the snow goose’s winter habitats, the goose faces no significant natural predation. 答案是B,不是很懂，望高手指教
Some species of Arctic birds are threatened by recent sharp increases in the population of snow geese, which breed in the Arctic and are displacing birds of less vigorous species.Although snow geese are a popular quarry for hunters in the southern regions where they winter, the hunting season ends if and when hunting has reduced the population by five percent, according to official estimates.Clearly, dropping this restriction would allow the other species to recover.
highlight部分暗含的一个推理是：restriction---->more SG---->threaten other species ,只有B选项指出不是限令导致了雪鹅数量的增长，所以weaken.
Which of the following, if true, most seriously undermines the argument?
A.Hunting limits for snow geese were imposed many years ago in response to a sharp decline in the population of snow geese.
B.It has been many years since the restriction led to the hunting season for snow geese being closed earlier than the scheduled date. 自限令使对雪鹅的扑杀提前结束已经很多年了，但雪鹅数量是最近才又一个急剧增长，并对其他鸟类造成威胁，说明并不是限令造成了雪鹅数量的增长，因此取消限令也不会造成其他鸟类物种数量的回升。 这里最关键的是看清题目里的recent sharp increases 和选项里的it had been many years ,时间概念上的转换，需要仔细的阅读题目。
自限令使对雪鹅的扑杀提前结束已经很多年了，但雪鹅数量是最近才又一个急剧增长，并对其他鸟类造成威胁，说明并不是限令造成了雪鹅数量的增长，因此取消限令也不会造成其他鸟类物种数量的回升。 这里最关键的是看清题目里的recent sharp increases 和选项里的it had been many years ,时间概念上的转换，需要仔细的阅读题目。
C.The number of snow geese taken by hunters each year has grown every year for several years.
D.As their population has increased, snow geese have recolonized wintering grounds that they had not used for several seasons.
E.In the snow goose’s winter habitats, the goose faces no significant natural predation.
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发表于 2010-3-2 15:30:13
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