GWD-17-Q11

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.

has reduced the population by five percent，dropping this restriction 也就是要是5%这个比率下降吗？也就是说每次猎杀的百分比要减少？也就说要保留更多的snow geese?那岂不是要伤害更多的其他的动物，怎么会allow the other species to recover？

B怎么削弱了？

题中的一个隐含假设：是官方的禁令促使猎人停止捕猎snow geese

 要weaken，就要从根本上推翻这个假设：如果是猎人自己不想再捕杀snow geese了，属于自发行为，而不是因为政府的禁令呢？

 B 好多年以来，实际停止捕猎的日期比官方规定的要早，说明在禁猎期之前，猎人就已经自发停止了捕猎，所以禁令取消与否，作用不大。