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. 答案选的是B,我选了C,个人无法理解restriction已经存在很长时间了如何可以削弱结论呢？ 谢高手指点！作者: sdcar2010 时间: 2011-7-6 22:59
the restriction led to作者: Rainbeauty 时间: 2011-7-6 23:59
提示: 作者被禁止或删除 内容自动屏蔽作者: sdcar2010 时间: 2011-7-7 00:21
B. It has been many years since the restriction led to the hunting season for snow geese being closed earlier than the scheduled date
In other words, what B says is that the 5% reduction in geese population due to hunting has never been reached for many years. Since B means hunters could not kill more than 5% of snow geese in a hunting season for many years, more than 5% reduction in geese population is unlikely to be reached even if such restriction is removed. In terms of grammar, It has been many years since (an event happened at a time in the past), simply means the time that event did happen was a long time ago.
Thus, answer B claims that the restriction set has no effect on the highest number of geese killed in a hunting season. Therefore, removing the restiction would not lead to more killings of the geese and better chances for the other species to recover. B weakens the argument.
If the hunting season was not closed early last year, that means the loss of the geese was below 5% of their population due to hunting.
Then if you remove the restiction of "only 5% of geese can be shot down each year," what kind of effect would you have on the geese population?
Nothing! Because the same hunters would show up and shot down the same number of geese - less than 5% of the total, just like what happened last year.作者: iamdurant 时间: 2011-7-7 00:48
really appreciate your help!!!