The Earth’s daily clock, measured in a single revolution, is twenty-four hours. The human clock, 【C1】______, is actually about t

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问题    The Earth’s daily clock, measured in a single revolution, is twenty-four hours. The human clock, 【C1】______, is actually about twenty-five hours. That’ s【C2】______scientists who study sleep have determined from human subjects who live for several weeks in observation chambers with no【C3】______of day or night. Sleep researchers have【C4】______other surprising discoveries as well.
   We spend about one-third of our lives asleep, a fact that suggests sleeping, 【C5】______eating and breathing, is a fundamental life process. Yet some people almost never sleep, getting by on as【C6】______as fifteen minutes a day. And more than seventy years of【C7】______into sleep deprivation, in which people have been kept【C8】______for three to ten days, has【C9】______only one certain finding: Sleep loss makes a person sleepy and that’s about all; it causes no lasting ill【C10】______. Too much sleep, however, may be【C11】______for you.
   These findings【C12】______some long-held views of sleep, and they【C13】______questions about its fundamental purpose in our lives. In【C14】______, scientists don’t know just why sleep is necessary.
   Some scientists think sleep is more the result of evolutionary habit than【C15】______actual need, Animals sleep for some parts of the day perhaps because it is the【C16】______thing for them to do: it keeps them【C17】______and hidden from predators; it’s a survival tactic. Before the advent of electricity, humans had to spend at least some of each day in【C18】______and had little reason to question the reason or need for【C19】______. But the development of the electroencephalograph and the resulting discovery in 1937 of dramatic【C20】______in brain activity between sleep and wakefulness opened the way for scientific inquiry in the subject.
【C4】

选项 A、come up against
B、come down to
C、come up with
D、come up to

答案C

解析 本题考查短语辨析。此处句意为“睡眠研究者们还______了其他令人惊讶的发现”。come up against指突然或意外碰到困难或反对等,come down to“归结为”,come up with“提出,拿出,发现”,come up to“比得上,达到”。根据意思,C.come up with符合题意,为正确答案。
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