In the late 1980s, the population of sea otters in the North Pacific began to decline. There are two plausible explanations for the decline: predation, possibly by killer whales, or disease. Of these two, disease is the more likely, since a concurrent sharp decline in populations of seals and sea lions is believed to have been caused by disease, and diseases that infect these creatures are likely to be able to infect sea otters also.
Which of the following, if true, most seriously weakens the reasoning?
(A) Killer whales in the North Pacific usually prey on seals and sea lions but will, when this food source is scarce, seek out other prey. (B) There is no indication that the sea otter population at any North Pacific location declined in the 1980s because of substantial numbers of sea otters migrating to other locations. (C) Along the Pacific coast of North America in the 1980s, sea otters were absent from many locations where they had been relatively common in former times. (D) Following the decline in the population of the sea otters, there was an increase in the population of sea urchins, which are sea otters' main food source. (E) The North Pacific populations of seals and sea lions cover a wider geographic area than does the population of sea otters. 答案是选A，可我认为A只是陈述了一个事实，说鲨鱼在海獭不多的时候吃别的生物，它没有证明是鲨鱼把海獭全吃完了啊。 我选的是C，我认为C说它的消失是有规律的行为，反驳了海獭的消失是突然的疾病造成的，从而割裂了因果之间的关系，反驳了结论。 我的思路哪里错了，求指教啊作者: alu1u 时间: 2012-10-6 13:05
我的看法：
