2013年12月英语四级考试完形填空练习（54）
2013年12月英语四级考试完形填空练习（54）Sleep is divided into periods of so-called REM sleep, characterized by rapid eye movements and dreaming, and longer periods of non-REM sleep.1kind of sleep is at all well-understood, but REM sleep is2to serve some restorative function of the brain. The purpose of non-REM sleep is even more3. The new experiments, such as those4for the first time at a recent meeting of the Society for Sleep Research in Minneapolis, suggest fascinating explanations5 non-REM sleep.
For example, it has long been known that total sleep6is 100 percent fatal to rats, yet,7examination of the dead bodies, the animals look completely normal. A researcher has now8the mystery of why the animals die. The rats9bacterial infections of the blood,10their immune systems – the self-protecting mechanism against diseases-had crashed.
Vitamins are organic compounds necessary in small amounts in the diet for the normal growth and maintenance of life of animals, including man. They do not provide energy,11do they construct or build any part of the body. They are needed for12foods into energy and body maintenance. There are thirteen or more of them, and if13is missing a deficiency disease becomes14. Vitamins are similar because they are made of the same elements – usually carbon, hydrogen, oxygen, and15nitrogen. They are different16their elements are arranged differently, and each vitamin17one or more specific functions in the body.18enough vitamins is essential to life, although the body has no nutritional use for 19vitamins. Many people,20, believe in being on the “safe side” ad. thus take extra vitamins. However, a well-balanced diet will usually meet all the body’s vitamin needs.
1. A. Either B. Neither C. Each D. Any
2. A. intended B. required C. assumed D. inferred
3. A. subtle B. obvious C. mysterious D. doubtful
4. A. maintained B. described C. settled D. afforded
5. A. in the light of B. by virtue of C. with the exception of D. for the purpose of
6. A. reduction B. destruction C. deprivation D. restriction
7. A. upon B. by C. through D. with
8. A. paid attention to B. caught sight of
C. laid emphasis on D. cast light on
9. A. develop B. produce C. stimulate D. induce
10. A. if B. as if C. only if D. if only
11. A. either B. so C. nor D. never
12. A. shifting B. transferring C. altering D. transforming
13. A. any B. some C. anything D. something
14. A. serious B. apparent C. severe D. fatal
15. A. mostly B. partially C. sometimes D. rarely
16. A. in that B. so that C. such that D. except that
17. A. undertakes B. holds C. plays D. performs
18. A. Supplying B. Getting C. Providing D. Furnishing
19. A. exceptional B. exceeding C. excess D. external
20. A. nevertheless B. therefore C. moreover D. meanwhile
答案解析：
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编辑推荐： 2013年12月英语四级考试完形填空练习汇总（100篇）
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