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  3. A Biological Clock Every living thing has what scientists call a biological clock that controls behavior. The biological cloc

A Biological Clock Every living thing has what scientists call a biological clock that controls behavior. The biological cloc

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问题                                A Biological Clock
   Every living thing has what scientists call a biological clock that controls behavior. The biological clock(1)plants when to form flowers and when the flowers should open. It tells insects when to(2)the protective cocoon (防护卵袋) and fly away, and it tells animals and human beings when to eat, sleep and wake.
   Events outside the plant and animals(3)the action of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur because of the(4)of hours of daylight. In the short(5)of winter, its fur becomes white. The fur becomes gray brown in(6)in the longer hours of daylight in summer.
   Inner signals control other(7)clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration(8)twice each year, Birds(9)from flying become restless when it is time for the trip,(10)they become calm again when the time of the flight has ended.
   Scientists say they are beginning to learn which(11)of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain(12)to control the timing of some of our actions. These(13)tell a person when to wake, when to(14), and when to seek food. Scientists say there probably are other biological clock cells that(15)other body activities.
选项 A、reach
B、leave
C、escape
D、enter
答案B
解析 解题思路：利用备选项的特点(C常用作不及物动词)对备选项进行排除(空格后是宾语成分，因此排除C)，缩小答案范围。再根据局部相关结构的语意(并列结构，含义为“什么时候……防护卵袋飞走”)判断B是答案。
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本试题收录于： 职称英语卫生类B级题库职称英语分类
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