Every living thing has what scientists call a biological clock that controls

游客2023-09-07  29

问题    Every living thing has what scientists call a biological clock that controls behavior. It tells plants when to 【C1】______ flowers and insects when to leave protective cocoon(茧) and fly away. And it tells animals and human beings when to 【C2】______ , sleep and seek food. It controls our body temperatures, the  【C3】______  of some hormones and even dreams.  
   Events 【C4】______ the plant and animal affect its actions. Scientists recently found that a tiny animal called Siberian hamster changes the color of its  【C5】______  because of the number of hours of 【C6】______ . In shorter days of winter its fur becomes white. The fur becomes gray-brown in longer 【C7】______ of daylight in summer.  
     【C8】______  signals control other biological clocks. German scientists found that some internal one seems to order birds to begin their  【C9】______    flights two times each year. Birds prevented from flying become 【C10】______ when it is time for the trip.  【C11】______  they become can again when the time of the flight has ended. A mix of outside and internal events controls some biological clocks;such things as heartbeat and the daily change from sleep to walking take place because of both external and internal signals.  
   Scientists are beginning to learn 【C12】______ parts of the brain contain the biologicaI clocks. A researcher at Harvard University. Dr. Martin Moore Ede, said a small group of cells near the front of the brain seemed to control the 【C13】______ of some of our actions. Probably there are other cells to control other body activities. He is studying 【C14】______ they affect the way we do our work. Most of us have great difficulty if we 【C15】______ often change to different work hours. 【C16】______ call take many days for a human body to 【C17】______ a major change in work hours. Industrial officials should have a better 【C18】______ of biological clocks and how they affect workers. He said such an understanding could 【C19】______ sickness and accidents at work, and would help increase 【C20】______ .    [br] 【C11】

选项 A、And
B、So
C、Then
D、But

答案 D

解析 连接词辨析题。由上题我们知道了空格前后两句话是转折关系:当迁徙时间已到,而又被阻止不能迁徙的鸟类很不平静.而当鸟类迁徙结束后它们又恢复了平静,故D正确。  
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