The disappearance of Steller’s sea cow from the Bering and Copper islands by 1768 has long been blamed on intensive hunting. But

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问题     The disappearance of Steller’s sea cow from the Bering and Copper islands by 1768 has long been blamed on intensive hunting. But its disappearance took only 28 years from the time Steller first described the species, a remarkably short time for hunting alone to depopulate the islands, especially given the large populations initially reported. However, by 1750, hunters had also targeted nearby sea otter populations. Fewer otters would have allowed sea urchin populations on which the otters preyed to expand and the urchins’ grazing pressure on kelp forests to increase. Sea cows were totally dependent on kelp for food, and within a decade of the onset of otter hunting, Steller noted that the islands’ sea cows appeared malnourished.
Which of the following can be inferred from the passage about kelp forests in the Bering and Copper islands between 1750 and 1768?

选项 A、They were reduced significantly.
B、They disappeared entirely from the region.
C、They were the primary food source for sea otters.
D、They were harvested in record numbers by humans
E、They increased pressure on sea urchin populations.

答案A

解析 根据原文,海藻数量在1750—1768年之间因为海胆的数量上升而减少了,因此选项A正确。
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本试题收录于: GRE VERBAL题库GRE分类
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