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  3. Every living thing has an inner biological clock that controls behavior. The clock works all the time; even when there are no ou

Every living thing has an inner biological clock that controls behavior. The clock works all the time; even when there are no ou

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问题     Every living thing has an inner biological clock that controls behavior. The clock works all the time; even when there are no outside signs to mark the passing of time. The biological clock tells plants when to form flowers and when the flowers should open. It tells insects when to leave the protective cocoon and fly away. And it tells animals when to eat, sleep and wake. It controls body temperature, the release of some hormones and even dreams. These natural daily events are circadian rhythms.
    Man has known about them for thousands of years. But the first scientific observation of circadian rhythms was not made until 1729. In that year a French astronomer, Jean Jacques d’Ortous de Mairan, noted that one of his plants opened its leaves at the same time every morning, and closed them at the same time every night. The plant did this even when he kept it in a dark place all the time.
    Later scientists wondered about circadian rhythms in humans. They learned that man’s biological clock actually keeps time with a day of a little less than 25 hours instead of the 24 hours on a man-made clock.
    About four years ago an American doctor, Eliot Weitzman, established a laboratory to study how our biological clock works. The people in his experiments are shut off from the outside world. They are free to listen to and live by their circadian rhythms. Dr. Weitzman hopes his research will lead to effective treatments for common sleep problems and sleep disorders caused by aging and mental illness.
    The laboratory is in the Montefiore Hospital in New York City. It has two living areas with three small rooms in each. The windows are covered, so no sunlight or moonlight comes in. There are no radios or television receivers. There is a control room between the living areas. It contains computers, one-way cameras and other electronic devices for observing the person in the living area. A doctor or medical technician is on duty in the control room 24 hours a day during an experiment. They do not work the same time each day and are not permitted to wear watches, so the person in the experiment has no idea what time it is.
    In the first four years of research, Dr. Weitzman and his assistant have observed 16 men between the ages of 21 and 80. The men remained in the laboratory for as long as six months. Last month, a science reporter for The New York Times newspaper, Dava Sobel, became the first woman to take part in the experiment. She entered the laboratory on June 13th and stayed for 25 days. Miss Sobel wrote reports about the experiment during that time, which were published in the newspaper.
In his observation, the French astronomer noticed that the leaves of a certain plant maintained its opening-and-closing cycles
选项 A、even when it was put in a murky place all day.
B、even if it was placed in the moonlight.
C、even when he was observing it from a dark place.
D、even if it was kept in a dark place from time to time.
答案A
解析 事实细节题。答案依据是第二段最后一句The plant did this even when he kept it in a dark place all the time，其中did this即指上一句提到的在每天早上的同一时间张开叶子，并且在每天晚上的同一时间闭合叶子。[A]中的murky与原文中的dark同义，all day与原文中的all the time同义复现，因此该项为正确选项。[D]为强干扰项，但from time to time与原文中的all the time意义相差甚远，故排除。
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