2. 外语
  3. The term biological clock is【B1】_____to the means by which living things【B2】_____their activity patterns, without any【B3】_____cu

The term biological clock is【B1】_____to the means by which living things【B2】_____their activity patterns, without any【B3】_____cu

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问题     The term biological clock is【B1】_____to the means by which living things【B2】_____their activity patterns, without any【B3】_____cue, to the time of day, or the month, or the year. The biological clocks seem to be beautifully【B4】_____to the needs of living things. They are【B5】_____ but little, if at all, by drugs, chemicals, or wide temperature difference—factors which may alter substantially the rates of all ordinary【B6】_____ of the body.
    The nature of the biological clocks’ mechanism is still a【B7】_____. Two quite different theories can【B8】_____ for them. According to the first of these theories, 【B9】______. This is believed to have evolved, aided by natural selection, as an adaptation to the rhythmic environment. It has now become independent of the environment. 【B10】______. The setting of their biological clocks, therefore, involves a constant adjustment to subtle environment forces. But the search for the specific timing system has been futile thus far. 【B11】______
【B11】
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答案Not only has no independent timing system ever been discovered, but there has not yet been even a guess as to its nature
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