Along with the Fairbanks samples, the researchers collected DNA from bones of 37 dog specimens(标本)from Mexico, Peru, and Bolivia that existed before the arrival of Columbus. In the case of both the Alaska dogs and the dogs from Latin America, the researchers found that they shared the most genetic material with gray wolves of Europe and Asia. This supports the idea of domestic dogs entering the New World with the first human explorers who wandered east over the land bridge.

　　Leonard and Wayne’s study suggests that dogs joined the first humans that made the adventure across the Bering Land Bridge to slowly populate the Americas. Wayne thinks the dogs that made the trip must have provided some excellent service to their human companions or they would not have been brought along. “Dogs must have been useful because they were expensive to keep, ”Wayne said. “They didn’t feed on mice; they fed on meat, which was a very guarded resource. ”

　　【文章大意】本文是科普性文章。说明了在几千年前狗陪同人们一起跨过白令大陆桥进入北美大陆, 并且在此繁殖起来。而通过检测发掘出的狗骨头的DNA也证实了这一点。

　　5. The underlined word“remains”is closest in meaning to“　”.

　　A. leftover foodB. animal waste

　　C. dead bodies

　　D. living environment

　　【解析】选C。词义猜测题。根据第四段第二句话“Leonard, an evolutionary biologist, collected DNA from 11 bones of ancient dogs that were locked in permafrost”说明是在永冻层发现的狗的骨头, 所以remains应该是尸体。故C正确。

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