When the head begins to heat up, yawning acts as a natural "thermostat" by allowing cool air to rush in and bring the brain back down to a healthy temperature, research suggests.

科学家研究发现，当人的大脑开始出现过热时，打呵欠的动作就充当天然的“自动调温器”，让清凉的空气进入大脑，使大脑温度恢复到健康水平。

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You could follow the crowd by working hard and keeping your head down, but will this get you the enhanced career you feel you deserve?

你可以和其他人一样埋头苦干，不过这样做，你能得到你认为自己应该得到的更好的工作机会吗？

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The child may respond to a teacher's request for quiet or control by looking away, putting his or her head down on the desk, orsimply ignoring the teacher.

孩子可能以冷漠和撇过去不看他们作为对老师要求的回应，低头对着桌子，直接无视老师的存在。

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And so, to play Larry, skilled clown Sean Hayes ("Will and Grace") transforms himself by shaving his head down the middle, letting prickly tufts of Larry-like hair protrude on the sides.

CNN: Review: 'The Three Stooges' is the Farrellys' labor of love

The movie jumps ahead in short, spiky scenes, punctuated by beautifully edited montages of digitized photographs and newspaper articles, and by Mara, head down in the wind, tearing through Sweden on a motorcycle like well, like a bat out of hell.

NEWYORKER: The Girl with the Dragon Tattoo

The Lions head Down Under again in 2013 determined to avenge their defeat by the Australians in 2001.

CNN: Lions skipper Warburton out of Barbarians warm-up