1.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.

很多實驗證據(jù)證實了打哈欠的另一個不同的功能，它能讓我們做好準(zhǔn)備，改變活動狀態(tài)。

2.A growing body of research now shows that yawning is nature's way of keeping our brains cool.

越來越多的研究表明，打哈欠是一種讓大腦保持冷靜的自然方式。

3.It might be that yawning helps to clear out the lungs by periodically lowering the pressure in them.

打哈欠可能通過周期性地降低肺部的壓力來幫助清理肺部。

4.Yawning may be part of that.

而打哈欠就是其中一部分。

5.No time had been found for yawning that day, either!

那天也沒人有時間打呵欠！

6.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.

當(dāng)志愿者在正常的空氣中、純氧的環(huán)境下，或者混有超過正常的二氧化碳含量的空氣中呼吸時，他們被要求要想著打哈欠。

7.Experiments have also cast serious doubt on the belief that yawning is triggered by a drop in blood oxygen or a rise in blood carbon dioxide.

對于打哈欠是由血液中的氧氣減少或血液中的二氧化碳增加引起的這種觀點，一些實驗也同樣提出了嚴(yán)重的質(zhì)疑。

8.Will you be kind enough to give a penny to a poor boy who is yawning from hunger?

你可以給一個因饑餓而打哈欠的可憐孩子一個便士嗎？

9.A completely different theory holds that yawning assists in the physical development of the lungs early in life, but has no remaining biological function in adults.

另一種完全不同的理論認為，打呵欠有助于生命早期肺部的生理發(fā)育，但對成年人沒有任何剩余的生理功能。