单选题
.Throughout history man has observed such natural cycles as the rising and setting of the sun, the ebb and flow of the ocean tides, and the changes of the seasons. The
1 nature of these events provided people with a measure of
2 about things to come and give them reason to reflect on their past and plan for their future. The regularity of such social activities as work hours, meal times, and holiday schedules
3 the extent to which human activity itself is organized in cycles.
Recently,
4 effort has been spent investigating the effect of various biological rhythms in the human body.
5 , interest in these rhythms at least in part results from man's basic desire to predict future behavior.
The human body
6 a number of repeatable rhythms: heartbeats, breathing rates, brain waves and other physiological processes within the human machine.
Scientists studying rhythms in humans have measured sleep patterns and attention
7 over periods of several days, and have
8 the fact that the cycles exist and exert effects on physiological and sociological behavior. A common example is jet lag. A person's traveling in the east-west direction across time zones
9 his sleep cycles—it may take several days to return to the
10 cycle or to readjust to a new one.
- A.indicates E. considerable I. Certainly M. security
- B.demonstrated F. upsets J. Thankfully N. exhibits
- C.verifying G. disappoints K. spans O. limits
- D.normal H. periodic L. gorgeous
【正确答案】
【答案解析】 此处填入修饰nature的词，可能是名词、形容词或分词。空格后的these events指的就是第一句提到的natural cycles“自然周期”所表现的现象。因此，空格处应填入含有“循环；周期”意思的词语，故用形容词periodic“周期(性)的”。
[参考译文]
纵观历史，人类观察着自然周期规律，例如日出日落、潮起潮落、四季更替。这些现象的周期性让人们对即将到来的事物有了不少的安全感，也给予了人们反思过去和计划未来的理由。这些社会活动——如工作时间、吃饭时间和假日安排——的规律性表明了某种程度上人类活动本身的组织安排也是有周期性的。
近年来，人们花费了大量精力来研究人体各种生物节律的作用。当然，对这些节律的兴趣至少有一部分是来自人们想要预测未来行为的基本欲望。
人体有着许多重复的节奏：心跳、呼吸率、脑波和其他人体机能的生理过程。
研究人体节奏的科学家对睡眠模式和注意力集中时间进行了数天的周期测量，并证明了一个事实：周期存在而且在生理和社会行为上发挥着作用。一个常见的例子就是时差。自东向西跨时区的旅行就会扰乱游客的睡眠周期——这可能要花上好几天的时间才能恢复到正常周期或再调整一个新周期。