2. 外语
  3. Small dogs generally live longer than big dogs so that small Yorkshire terrier (猎狐狗) next door could be around for a long time.

Small dogs generally live longer than big dogs so that small Yorkshire terrier (猎狐狗) next door could be around for a long time.

admin2013-06-02  21
问题     Small dogs generally live longer than big dogs so that small Yorkshire terrier (猎狐狗) next door could be around for a long time. But body size isn’t the only factor that【B1】______how long dogs survive. Personality influences life span, too, according to a new study that might help explain how animal【B2】______evolve.
    Study on animals from ants to apes has found that different【B3】______have different personalities. Some are timid, others【B4】______. Biologists have proposed that temperaments (性情) evolved along with life history.【B5】______, violent animals use a lot of energy fast in【B6】______short lives, the thinking goes, whereas calmer animals last longer, saving themselves to【B7】______ later in life. But it’s hard to run evolutionary【B8】______on these personalities in anything longer lived than a fruit fly. So evolutionary biologist Vincent from Canada came up with an idea about dogs. "All these breed differences reflect an experiment on artificial selection," says Vincent.【B9】______—the ability to chase foxes into holes, or herd sheep, or sit attractively on a sofa.
    But evolutionary physiologist Joseph Williams of Ohio State University in Columbus isn’t convinced that 【B10】______. "For me, it still remains to be seen. Dogs are contrary to what you would expect in nature in terms of longevity," he says.【B11】______. On the other hand, a Chihuahua will generally outlast a Saint Bernard.
【B9】
选项
答案The huge diversity of dogs resulted not from natural selection, but from generations of humans selecting animals with traits
解析 huge, diversity, resulted, natural selection, humans, selecting, traits
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