Q11:

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?

1. The illegal lobster harvesting was not so extensive that the population of catchable lobsters in Belukia’s territorial waters had sharply declined by 1996.
2. The average annual lobster catch, in tons, of an outlaw fishing boat has increased steadily since 1992.
3. Outlaw fishing boats do not, as a group, harvest more lobsters than do licensed lobster-fishing boats.
4. The annual legal lobster harvest in Belukia in 1996 was not significantly less than 9,000 tons.
5. A significant proportion of Belukia’s operators of licensed lobster-fishing boats went out of business between 1992 and 1996.

本题答案是A..我觉得A起到的是WEAKEN的作用：

因为文章的逻辑关系是说在being no reduction in the level of legal lobster fishing activity（捕获龙虾活动不变的情况下）, the local catch was 9,000 tons below pre-1992 levels（捕获量减少了９０００吨），从而推出这９００吨的龙虾是非法捕获的。

　A是说龙虾在Belukia’s territorial waters 中的数量减少了。。这说明龙虾本身的数量减少也可能到减少９０００吨的捕获量，从而　weaken原来的结论。。。

请赐教！！

A怎么会是weaken呢，A的意思是说非法捕鱼的数量还没有多到1996年可捕鱼的数量下降。也就是说1992年和1996年可捕鱼的总数一样，但1996年少了9000吨，这样就可以得出结论，这9000吨是非法捕鱼得了。

如果否定了A，即1992与1996年可捕鱼的总量不同，则原结论不能成立。