Again the implication is that yawning has little or nothing to do with oxygen.
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3. 微笑、皱眉、挑眉、打哈欠和冷笑都传达信息。
A smile, frown, raised an eyebrow, yawn, and sneer all convey information.
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4. 这一理论的支撑来自对日常生活中打哈欠行为的研究。
Support for this theory came from a study of yawning behavior in everyday life.
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5. 有人提出，打哈欠和打嗝可能有助于清理胎儿的气道。
It has been suggested that yawning and hiccupping might serve to clear out the fetuses airways.
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6. 你可以给一个因饥饿而打哈欠的可怜孩子一个便士吗？
Will you be kind enough to give a penny to a poor boy who is yawning from hunger?
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7. 打哈欠可能通过周期性地降低肺部的压力来帮助清理肺部。
It might be that yawning helps to clear out the lungs by periodically lowering the pressure in them.
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8. 越来越多的研究表明，打哈欠是一种让大脑保持冷静的自然方式。
A growing body of research now shows that yawning is nature's way of keeping our brains cool.
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9. 让科学家们感到困惑的一个更大的问题是，我们究竟为什么会打哈欠。
A bigger question puzzling scientists is why we yawn at all.
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10. 也许这是打哈欠进化为社交线索的一种暗示——“到我们大家睡觉的时间了”。
That may be a hint that yawn evolved as a social cue—"time for us all to go to bed".
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11. 很多实验证据证实了打哈欠的另一个不同的功能，它能让我们做好准备，改变活动状态。
The empirical evidence, such as it is, suggests an altogether different function for yawning—namely, that yawning prepares us for a change in activity level.
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12. 疲劳理论的另一个缺陷是，打哈欠并不能像该理论所预测的那样，提高警觉性或生理活跃度。
Another flaw of the tiredness theory is that yawning does not raise alertness or physiological activity, as the theory would predict.
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13. 在美国也有类似的情况，当有人提到棒球时，有些人会打哈欠甚至皱眉，你可能就是其中之一。
A similar situation exists in America, where there are those individuals you may be one of them who yawn or even frown when somebody mentions baseball.
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14. 在美国也有类似的情况，当有人提到棒球时，有些人会打哈欠甚至皱眉，你可能就是其中之一。
A similar situation exists in America, where there are those individuals you may be one of them who yawn or even frown when somebody mentions baseball.
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15. 在你打哈欠、揉眼睛、准备打盹之前，想一想生活在一个瞌睡虫遍地的国家是怎样的一个情况吧。
Before you yawn, rub your eyes and hit the snooze button, consider the consequences of living in a nation of sleepheads.
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.
Another experiment demonstrated that physical exercise, which was sufficiently vigorous to double the rate of breathing, had no effect on the frequency of yawning.
This accords with anecdotal evidence that people often yawn in situations where they are neither tired nor bored, but are preparing for impending mental and physical activity.
Volunteers were told to think about yawning while they breathed either normal air, pure oxygen, or an air mixture with an above-normal level of carbon dioxide.
Volunteers were told to think about yawning, while they breathed either normal air, pure oxygen, or an air mixture with an above-normal level of carbon dioxide.
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22. 她打哈欠是对我打哈欠的条件反射。
Her yawn was a Pavlovian response to my yawn.
《牛津词典》
23. 然而，打哈欠与睡眠模式没有关系。
Yawning bore no relationship to sleep patterns, however.
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24. 他们开始打哈欠，我们也开始打哈欠。
They start to yawn, and we start to yawn.
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25. 房间里的人在打哈欠，或者在替自己搔痒。
The occupants of the rooms are yawning, or else scratching themselves.
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26. 当你看到有人打哈欠时，你也会开始打哈欠，你知道这是怎么回事吗?
Do you know how it is when you see someone yawn and you start yawning too?
If the theory was correct, breathing air with extra carbon dioxide should have triggered yawning, while breathing pure oxygen should have suppressed yawning.
