Yawning sends out certain messages -either “Oh ，this movie is so boring” or “I probably need to get some sleep”. But did you know that a yawn can also help your brain to cool down when it is overheated?
A new study, led by a research team at Princeton University, has indicated that yawning could be the brain’s natural way of regulating temperature. People yawn more often when the temperature outdoors is lower than their body temperature but are less likely to yawn when it is hotter outdoors, according to Sciencedaily. .
The research team did an experiment on 160 people, 80 in summer and 80 in winter, to examine how often they yawned at different air temperatures. The study found that people yawned more often in winter than in summer. Scientists say that when the air temperature is lower outside the body, there is heat exchange between the overheated brain and the cool air. But when the air temperature is higher than or equal to the body, people are less likely to yawn because the hot air they breathe in will make the brain even hotter.
When people yawn, their jaw is also stretched ，which increases blood flow and may also help cool the brain
The study showed that the amount someone yawned could be related to the amount of time they spent outside. The longer they spent outside in summer, the less they yawned. Nearly 40 percent of participants yawned within their first five minutes outside, but after that the percentage was reduced to less than 10 percent.
However, the result was the opposite in winter. The number of people who yawned increased when they spent more than five minutes outdoors. But the change was only slight pared to summertime.
According to Gallup, this is the first report to show that yawning frequencies change depending on season. This could help us to understand better the way our brains work. It may also help us understand the reason why frequent yawning can sometimes be a sign of brain disease.
【小题1】The purpose of the experiment is .A． to prove people yawn in winter and in summer equallyB． to indicate brain can regulate temperature naturallyC． to find the frequency of people’s yawningD． to show the real reason why people yawn【小题2】The information we get from Paragraphs 5 and 6 is that .A． longer outdoor summertime results in more yawnsB． yawning frequency changes with outdoor timeC． yawning frequency increases with outdoor timeD． longer outdoor wintertime leads to fewer yawns【小题3】Acorrding to the text ，people yawn more often .
A, when the air temperature is lower outside the body
B. when the hot air breathed in makes the brain hotter
C. when the air temperature is higher than the body
D. when the air temperature is equal to the body
【小题4】What could be the best title for the text?A． Yawning Is A Sign of Brain DiseaseB． Yawning Carries Some InformationC． Yawning Benefits Your BodyD． Yawning Cools Your BrainC
网友回答
(答案→)C
解析：本文介绍了大脑调节温度的自然方法是打呵欠。当体温高于室温时，人们打呵欠的频率会增加，反之会降低，同时，打呵欠的频率变化取决于季节，夏季时人们在户外时前五分钟有近40%的参加实验的人会打呵欠，之后会降到不到10%，而冬季前五分钟打呵欠的人比夏季多，但之后和夏季的数据只有轻微变化。
【小题1】细节题：根据第三段中“ to examine how often they yawned at different air temperatures.”检查在不同的温度下打呵欠的频率。故选C。
【小题2】推理题：阅读第五第六段可知在户外打呵欠的频率有所改变。夏季时人们在户外时前五分钟有近40%的参加实验的人会打呵欠，之后会降到不到10%，而冬季前五分钟打呵欠的人比夏季多，但之后和夏季的数据有轻微变化。故选B。
【小题3】细节题：根据第二段中“ People yawn more often when the temperature outdoors is lower than their body temperature”当室外温度低于体温时人们会更多地打呵欠。故选A。
【小题4】推理题：阅读文章可知第二段中“A new study, led by a research team at Princeton University, has indicated that yawning could be the brain’s natural way of regulating temperature”普林斯顿大学的一个研究小组的一项最新研究表明打呵欠是大脑调节温度的自然方式，是文章主旨，全文围绕这一主题展开举例论述。故选D。