【托福阅读题型：The mystery of yawning句子简化题】托福阅读中句子简化题是重要题型之一。根据托福阅读题型不同来进行专项练习，是短期提高托福阅读能力的有效方法。同学们需要多加练习哦!

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　　托福阅读句子简化题：The mystery of yawning

　　【Paragraph 1】According to conventional theory, yawning takes place when people are bored or sleepy and　serves the function of increasing alertness by reversing, through deeper breathing, the drop in blood oxygen levels that　are caused by the shallow breathing that accompanies lack of sleep or boredom. Unfortunately, the few scientific　investigations of yawning have failed to find any connection between how often someone yawns and how much sleep　　they have had or how tired they are. About the closest any research has come to supporting the tiredness theory is to　confirm that adults yawn more often on weekdays than at weekends, and that school children yawn more frequently in　their first year at primary school than they do in kindergarten.(The mystery of yawning)

　　Which of the sentences below best expresses the essential information in the highlighted sentence in the passage?　Incorrect choices change the meaning in important ways or leave out essential information.

　　○ It is the conventional theory that when people are bored or sleepy, they often experience a drop in blood oxygen　levels due to their shallow breathing.

　　○ The conventional theory is that people yawn when bored or sleepy because yawning raises blood oxygen levels,　which in turn raises alertness.

　　○ According to conventional theory, yawning is more likely to occur when people are bored or sleepy than when they　are alert and breathing deeply.

　　○ Yawning, according to the conventional theory, is caused by boredom or lack of sleep and can be avoided through　deeper breathing.

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