GWD 11-40 值得讨论

Q40:

Parland’s alligator population has been declining
                in recent years, primarily because of hunting.  Alligators prey heavily on a species of freshwater fish that is highly valued as food by Parlanders, who had hoped that the decline in the alligator population would lead to an increase in the numbers of these fish available for human consumption.  Yet the population of this fish species has also declined, even though the annual number caught for human consumption has not increased.

Which of the following, if true, most helps to explain the decline in the population of the fish species?

1. The decline in the alligator population has meant that fishers can work in some parts of lakes and rivers that were formerly too dangerous.
2. Over the last few years, Parland’s commercial fishing enterprises have increased the number of fishing boats they use.
3. Many Parlanders who hunt alligators do so because of the high market price of alligator skins, not because of the threat alligators pose to the fish population.
4. During Parland’s dry season, holes dug by alligators remain filled with water long enough to provide a safe place for the eggs of this fish species to hatch.
5. In several neighboring countries through which Parland’s rivers also flow, alligators are at risk of extinction as a result of extensive hunting.

答案为：D但我认为应该是B

理由：因为即使D的条件成立，事实上成年的Alligator数目还是比以前下降了。而B则说明，虽然用于human consumption的没有变，但可能用于commercial的增加了，请大家讨论一下这样理解对么？

D是说Alligator和fish的数量有正相关性,因为Alligator可以帮助fish繁殖,所以A下降，fish也下降。我认为commercial fishing 属于human comsumption，这是典型的推翻前提的错误。

以下是引用hutty2000在2006-6-8 3:17:00的发言：
有道理！我是把D中的“this fish ”当成Alligator了，没看成是那个好吃的东东

no offense, but alligator is not fish