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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.
单选题26.Lindsay Eierman says she didn't sleep well last night because______.
单选题27.According to Paragraph 3, which of the following is NOT true about yawning?
【正确答案】
B
【答案解析】细节题。根据题干关键词定位到第三段。第三段第一句句意为“打哈欠可以让我们在感受到压力的时候使大脑处于警觉状态”，B项中的makes people relax和第一句中的keep our brains alert矛盾，故B项“它(打哈欠)让人们在压力下放松”不符合文意，故B项为正确答案。A项中的always happens in group与原文often occur in clusters是同义替换；C项中的is caused by与原文trigger是同义替换；D项中的usually lasts approximately与原文typically last about是同义替换，三项均符合原文，故排除。
单选题28.The word "contagion" (Para. 4) most probably means______.
单选题29.According to Dr. Gallup, people in a meeting may yawn when______.
【正确答案】
A
【答案解析】推断题。根据题干关键词定位到最后一段。根据末句中的diminish yawning和keep it air-conditioned可知，通过调低空调温度可以降低打哈欠频率，那么可以推断出会议室过热的时候人们容易打哈欠，故A项为正确答案，同时排除D项。B项“(当)周围的其他人打哈欠(的时候)”并不是盖洛普博士的观点。C项“(当)会议简短而有趣(的时候)”与原文意思相反。