We all know that the normal human daily cycle of activity is of some 7-8 hours’ sleep alternating with, some 16-17 hours’ wakefu

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问题      We all know that the normal human daily cycle of activity is of some 7-8 hours’ sleep alternating with, some 16-17 hours’ wakefulness and that, broadly speaking, the sleep normally coincides with the hours of darkness. Our present concern is with how easily and to what extent this cycle can be modified.
     The question is no mere academic one. The ease, for example, with which people earl change from working in the day to working at night is a question of growing importance in industry where automation calls for round-the-clock working of machines, It normally takes from five days to one week for a person to adapt to a reversed routine of sleep and wakefulness, sleeping during the day and working at night. Unfortunately, it is often the case in industry that shifts are changed every week; a person may work from 12 midnight to 8 a.m. one week, 8 a.m. to 4 p.m. the next, and 4p.m. to 12 midnight the third and so on. This means that no sooner has he got used to one routine than he has to change to another, so that much of his time is spent neither working nor sleeping very efficiently.
      The only real solution appears to be handed over the night shift to a number of permanent night workers. An interesting study of the domestic life and health of night-shift workers was carried out by Brown in 1957. She found a high incidence of disturbed sleep and other disorders among those on alternating day and night shifts, but no abnormal occurrence of these phenomena among those on permanent night work.
     The latter system then appears to be the best long-term policy, but meanwhile something may be done to relieve the strains of alternate day and night work by selecting those people who can adapt most quickly to the changes of routine. One way of knowing when a person has adapted is by measuring his body temperature. People engaged in normal daytime work will have a high temperature during the hours of wakefulness and low one at night; when they change to night work the pattern will only gradually go back to match the new routine and the speed with which it does so parallels, broadly speaking, the adaptation of the body as a whole, particularly in terms of performance Therefore, by taking body temperature at intervals of two hours throughout the period of wakefulness it can be seen how quickly a person can adapt to a reversed routine, and this could be used as basis for selection. So far, however, such a form of selection does not seem to have been applied in practice.
It is possible to find out if a person has adapted to the changes of routine by measuring his body temperature because ______.

选项 A、body temperature changes when the cycle of sleep and wakefulness alternates
B、body temperature changes when he changes to night shift or back
C、the temperature reverses when the routine is changed
D、people have higher temperatures when they are working efficiently

答案D

解析 要点定位题。根据第三段第三句,正常日班工作时工作效率高,体温也稍高。文章接着又说,改变工作安排之后,有一个适应过程,体温变动模式也随着适应程度的变化而变化,效率高时体温也高一些。这一点还可以从这一句最后的particularly in terms of performance中看出。而选项A不全面,没有指出体温变化与身体的适应程度大体上一致这一点,也没有指出可以根据其工作好坏来判断。
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