Yawning can be a problem at the office for Lindsay Eierman, which makes her embarrassed. "I’ve explained, ’I’m sorry, I didn’t g

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问题    Yawning can be a problem at the office for Lindsay Eierman, which makes her embarrassed. "I’ve explained, ’I’m sorry, I didn’t get much sleep last night,’" says Ms Eierman, a 26-year-old social worker from Durham, North Carolina. But a lack of sleep may not be the problem.
   Researchers are starting to unravel the mystery surrounding the yawn, one of the most common and often embarrassing behaviours. Yawning, they have discovered, is much more complicated than previously thought. Although all yawns look the same, they appear to have many different causes and to serve a variety of functions.
   Yawning is believed to be a means to keep our brains alert in times of stress. Contagious yawning appears to have evolved in many animal species as a way to protect family and friends, by keeping everyone in the group vigilant. Changes in brain chemistry trigger yawns, which typically last about six seconds and often occur in clusters.
   To unravel the mystery of yawning, scientists built upon early, observed clues. Yawning tends to occur more in summer. Most people yawn upon seeing someone else do it, but infants and people with autism or schizophrenia aren’t so affected by this contagion effect. And certain people yawn at surprising times, like parachutists who are about to jump out of a plane or Olympic athletes getting ready to compete.
   A leading hypothesis is that yawning plays an important role in keeping the brain at its cool, optimal working temperature. The brain is particularly sensitive to overheating, according to Andrew Gallup, an assistant professor of psychology at the State University of New York at Oneonta. Reaction times slow and memory wanes when the brain’ s temperature varies even less than a degree from the ideal 98.6 degrees Fahrenheit.
   There are some practical applications. Dr. Gallup said managers might want to keep in mind the brain-cooling role of yawning when a meeting is long and boring. "One way to diminish yawning frequency in an office would be to keep it air-conditioned. If it’s very cold in the room, yawning rates are going to be quite low," Dr. Gallup said.
The passage mainly discusses______.

选项 A、the rates of yawning
B、the misconceptions of yawning
C、the secrets of yawning
D、the applications of yawning

答案C

解析 主旨题。本题考查文章主旨。本文第二段首句和末句分别指出“研究人员目前正 逐渐揭开打哈欠的秘密”“……但实际上却有很多不同的成因,所以打哈欠的作用也不 尽相同”,说明了文章的中心。剩下的四段从打哈欠的作用、成因、应用等方面简要阐述。 第二段和第四段首句的mystery是直接的线索词,故C项“打哈欠的秘密”为正确答案。 A项“打哈欠的频率”和D项“打哈欠的应用”都是其中一个方面。B项“对打哈欠的误 解”只是第一段句末的引子,并非文章主要内容,故排除。
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