If your head is overheating, you are very likely to yawn(打哈欠) soon, according to a new study that has found the main purpose of yawning is to control brain temperature. The study explains several mysteries about yawning, such as why it’s most commonly done just before and after sleeping, why certain diseases lead to too much yawning, and why breathing though the nose often stops yawning.
“Brains are like computers,” Andrew Gallup, a researcher in the department of Biology at Binghamton University who led the study, said. “They operate best when cool.”
He and his co-workers Micheal Miller and Anne Clark did researches on yawning in parakeets(長尾小鸚鵡) , which have relatively large brains, live wild in Australia, often experience temperature changes, and, most importantly, do not yawn when others yawn, as humans and some other animals do.
For the study, the scientists put parakeets under three different conditions: increasing temperature, high temperature and normal temperature. While the frequency(頻率) of yawns did not increase under the latter two conditions, it increased greatly when the researchers increased the temperature.
It’s now believed yawning operates like a radiator(散熱器).
If air in the atmosphere is cooler than the brain and body temperatures, taking it in quickly cools blood, which in turn cools the brain. The new findings also explain why tired people often yawn. Both tiredness and sleep loss can increase brain temperature, while yawning can cool down the brain.
In the future, researchers may focus more on brain temperature and its role in diseases and their symptoms. But the new study on yawning changes the popular idea that yawns are just signs of getting tired of something.
49. What’s the best title for the passage?
A. Why don’t people yawn at normal temperature?
B. The yawn explained—it cools your brain.
C. Yawning operates like a radiator.
D. The cause of yawning—finally found out.
50. The main reason why researchers chose parakeets to do the research is that parakeets______.
A. have very large brains                
B. live wild in Australia
C. are not affected by others’ yawning       
D. experience frequent temperature changes
51. The writer may suggest doing all of the following to stop yawning EXCEPT______.
A. breathing through the nose          
B. turning up the heat
C. enjoying some cool wind               
D. putting a cold towel on your forehead
52. In which section of a newspaper would you most probably read this passage?
A. Discovery.        B. Education.         C. Health.              D. Mystery.


49---52   BCBA  

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科目：高中英語 來源：2011-2012學(xué)年浙江省杭州市高三3月月考英語試題 題型：完形填空

完形填空 (共20 小題；每小題1分；滿分20分)

  閱讀下面短文, 掌握其大意, 然后從 1---20各題所給的四個選項中,選出最佳選項.

Seven loyal readers came to the Teens' office two weeks ago. They had a wonderful day learning how to make a newspaper. But what   1   made them excited was that they had their say(發(fā)言權(quán)).

"What most   2   me was when I was saying something, I found all eyes were on me," said Tang Shining, one of the students. Her friend, Li Chunbei   3  , and felt very glad that when she was talking, the editors nodded and   4    took notes.

Students are happy to see the editors listen to their   5   . You may often   6   about being neglected（忽視） by teachers and parents.    7   before complaining please make sure that you have already spoken about your   8    .

Traditionally in China, teachers at school and parents were   9   the ones to tell teenagers what they should and shouldn't do. The young are   10   to doing what they are told, rather than thinking by themselves. But then their ideas would be locked in their brain and not be  11   .

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Sometimes, we need to let our   17  be heard, so others can understand our thoughts and feelings.

Don' t be afraid of being   18  for what you have done. You know it is your   19  to speak your mind. Even if your suggestions are denied, at least you have tried your best. You will not be left with any   20  .

1.A. really B. directly            C. completely               D. immediately

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①Asking family members to contribute more money if enough members don’t chip in

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③Paying using PayPal or a credit card

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A．②-①-③-④

B．①-③-②-④

C．②-④-①-③

D．②-③-④-①

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