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  3. Since there is such an abundance of food in the sea, it is understandable that some of the efficient, highly adaptable, warm-blo

Since there is such an abundance of food in the sea, it is understandable that some of the efficient, highly adaptable, warm-blo

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问题     Since there is such an abundance of food in the sea, it is understandable that some of the efficient, highly adaptable, warm-blooded mammals that evolved on land should have returned to the sea. Those that did do that have flourished. Within about 50 million years—no time at all, geologically speaking —one of the four kinds of mammals that has returned to a marine environment has developed into the largest of all animal forms, the whale. A second kind, the seal, has produced what is probably the greatest population of large carnivorous mammals on Earth. This suggests that these "top dogs" of the ocean are prospering and multiplying. However, such has not been the case, at least not for the last 150 years. Trouble has closed in on these mammals in the form of equally warm-blooded and even more efficient and adaptable predators, humans. At sea, as on land, humans have now positioned themselves on top of the whole great pyramid of life, and they have caused serious problems for the mammals of the sea.
    There is a simple reason for this. Marine mammals have the misfortune to be swimming aggregates of commodities that humans want: fur, oil, and meat. Even so, they might not be so vulnerable to human depredation if they did not, like humans, reproduce so slowly. Every year humans take more than 50 million tons of fish from the oceans without critically depleting the population of any species. But the slow-breeding mammals of the sea have been all but wiped out by humans seeking to satisfy their wants and whims.
It can be inferred from the passage that marine mammals are like humans in which of the following ways?
选项 A、They survive despite changes in their metabolic rates.
B、They reproduce slowly.
C、They are prospering and multiplying.
D、They are depleting the vegetation of the seas.
答案B
解析 根据文章第二段第三句“Even so，they might not be so vulnerable to human depredation if they didnot，like humans，reproduce so slowly．”可知，如果它们的繁殖速度不像人类那样缓慢，面对人类的掠夺它们也不会显得如此脆弱。所以可以推知海洋哺乳动物和人类的共同点就是繁殖速度缓慢。据此判断，答案是B。
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