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 word "contagion"(Para. 4)most probably means______.

选项 A、spreading
B、learning
C、protection
D、imitation

答案A

解析 含义题。根据题干关键词定位到第四段。contagion前面有代词this修饰,所以必 定有指代。本句是由but连接的两个分句,所以this指代的是第一个分句的现象,即“在 看到别人打哈欠时,大多数人也会不自觉这样做”,这是一种传染效应,故A项“传染、传 播”为正确答案。B项“学习”,C项“保护”,D项“模仿”均不正确。
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