13．People born in winter are more likely to suffer mental health disorders，according to a recent study carried out by researchers at Vanderbilt University in Tennessee．
Researchers raised baby mice from birth to weaning （断奶） in either"summer"light cycles of 16 hours of light and 8 hours of dark or"winter"cycles of 8 hours of light and 16 hours of dark．A third group experienced 12 hours of light and 12 hours of dark a day．
Then half the winter mice stayed in a winter cycle，while half switched to a summer schedule．The summer mice were similarly split．The mice raised in equal periods of light and dark were split into three groups，one of which stayed on the 12hour schedule，one of which joined the winter group，and one of which joined the summer group．
After 28 days，it turns out the summerborn mice behaved the same whether they stayed on the summer cycle or switched to winter．But among the winterborn mice，those stayed in winter kept their previous schedule，while those that switched to summer stayed active for an extra hour and a half，which indicates that mice born and weaned in a winter light cycle showed dramatic disruptions in their biological clocks．
The finding is the first of its kind in mammals，and it could explain why people born in winter are at higher risk for mental health disorders including bipolar depression，schizophrenia and seasonal affective disorder．
"We know that the biological clock regulates mood in humans，"said study researcher McMahon．"If the mechanism （机制） similar to the one that we found in mice operates in humans，the n it could not only have an effect on a number of behavioral disorders，but also have a more general effect on personality．"
32．How many groups of mice are there finally in all in the experiment？
A
A．Seven．B．Six．C．Five．D．Four．
33．What's the main idea of the text？D
A．The biological clock regulates mood in humans．
B．People born in winter are at higher risk for physical health disorders．
C．The length of light will influence the behavior of the mice．
D．Being born in winter has a negative effect on people's mental health．
34．The underlined word"split"（Paragraph 3）can be replaced byB．
A．ended B．divided C．hit D．torn
35．Who is the appropriate reader of the passage？C
A．A jobhunter．B．A student in the university．
C．A newlymarried couple．D．An experienced dentist．
A．A jobhunter．B．A student in the university．
C．A newlymarried couple．D．An experienced dentist．
分析 本文介绍了一项最新的研究结果，结果表明冬天出生的人更容易患心理疾病．
解答 32．A细节理解题．在第二段中提到了分成了三组，而在第三段中又将这三组分别分 成了两组、两组和三组，因此在实验中一共有七组老鼠．选A
33．D主旨大意题．通读全文可知，文章的第一段就开门见山地点明了本文的主旨People born in winter are more likely to suffer mental health disorders，即冬天出生的人更有可能存在心理障碍，因此选 D．
34．B 词义猜测题．根据第三段的第一句及画线词后面的"were split into three groups"可推知，"split"与"divided"同义，意为"被分开"．故选B
35．C 推理判断题．通读全文可知，本文告诉我们出生时间对人的精神健康的影响，再结合四个备选项可知，新婚夫妇应是最合适的读者，那样新婚夫妇可以在情况允许下选择孩子的出生时间．选C
点评 本文是科教类阅读理解．做这类题材阅读理解时要求考生对文章通读一遍，做题时结合原文和题目有针对性的找出相关语句进行仔细分析，结合选项选出正确答案．推理判断题也是要在抓住关键句子的基础上合理的分析才能得出正确答案，切忌胡乱猜测，一定要做到有理有据
