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发表于 2010-8-10 09:00:52 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式
In 1992 outlaw fishing boats began illegally harvesting lobsters from the territorial waters of the country of Belukia. Soon after, the annual tonnage of lobster legally harvested in Belukian waters began declining; in 1996, despite there being no reduction in the level of legal lobster fishing activity, the local catch was 9,000 tons below pre-1992 levels. It is therefore highly likely that the outlaw fishing boats harvested about 9,000 tons of lobster illegally that year.
Which of the following is an assumption on which the argument depends?
A. The illegal lobster harvesting was not so extensive that the population of catchable lobsters in Belukia’s territorial waters had sharply declined by 1996
B. The average annual lobster catch, in tons, of an outlaw fishing boat is has increased steadily since 1992.
C. Outlaw fishing boats do not, as a group, harvest more lobsters than do licensed lobster-fishing boats.
D. The annual legal lobster harvest in Belukia in 1996 was not significantly less than 9,000 tons.
E. A significant proportion of Belukia’s operators of licensed lobster-fishing boats were out of business between 1992 and 1996


答案A
求解释
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沙发
发表于 2010-8-10 09:11:24 | 只看该作者
在total不变的前提,如果正常的捕捞减少了9000吨,那么非法捕捞就捕了9000吨。
但是文章没有给出total不变的前提,那么如果total减少了,这个等式就不成立了。
板凳
 楼主| 发表于 2010-8-10 09:14:19 | 只看该作者
在total不变的前提,如果正常的捕捞减少了9000吨,那么非法捕捞就捕了9000吨。
但是文章没有给出total不变的前提,那么如果total减少了,这个等式就不成立了。
-- by 会员 wangsiwei (2010/8/10 9:11:24)



可是为什么 The illegal lobster harvesting was not so extensive 会导致 population of lobsters in Belukia’s territorial waters declined 呢
地板
发表于 2010-8-10 09:28:28 | 只看该作者
排除total因为过渡捕捞而减少的可能性。
5#
发表于 2010-8-13 18:21:48 | 只看该作者
他说的有道理的。只有Total不变,这边加9000,那边才会减9000。
关于你的疑问,我想说,过度捕捞确实会导致total population下降,可能是因为过度捕捞幼年龙虾,导致再生能力下降,并且题目之所以说非法捕捞1992年就开始了,就是因为给以上过程留出充分的时间。因为当年的过度捕捞只有第二年及以后才能看出来影响。
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