题目：
阅读下面的短文， 并根据短文后的要求答题（请注意问题后的字数要求）
_[1]If you think English means endless new words, difficult grammar and sometimes strange pronunciation, you are wrong. Haven’t you noticed that you have become smarter since you started to learn a language?
[2]According to a new study by a British university, learning a second language can lead to an increase in your brain power. Researchers found that learning other languages changes grey matter. This is the area of the brain which processes information. It is similar to the way that exercise builds muscles.
[3]The researchers also found the effect is greater on the younger people who learn a second language.
[4]A team led by Dr. Andrea Mechelli, from University College London, took a group of Britons who only spoke English. They were compared with a group of “early bilinguals(通两种语言的人)”, who had learnt a second language before the age of five, as well as a number of later learners.
[5]Scans showed that grey matter density（密度）in the brain was greater in bilinguals than in people without___________________. But the longer a person waited before mastering a new language, the smaller the difference was.
[6] “Our findings suggest that the structure of the brain is changed by the experience of learning a second language,” said the scientists.
[7]It means that the change itself increases the ability to learn.
[8]Professor Dylan Vaughan Jones of the University of Wales, has researched the link between bilingualism and maths skills. Having two languages gives you two windows on the world and makes the brain more flexible,” he said, “You are actually going beyond language and have a better understanding of different ideas.”
小题1:What is the best title for this passage? （no more than 10 words）
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小题2:Which sentence in the text is the closest in meaning to the following one?
Mastering two languages can broaden your views in the world and makes you clever.
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小题3:Fill in the blank in Paragraph 5 with proper words． （no more than 4 words）
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小题4:What does the word "they" Line2, Paragraph4） probably refer to? （no more than 5 words）
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小题5:What do you think of English learning after you read this passage?
（no more than 10 words）
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答案：
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下面是错误答案，用来干扰机器的。
由于概率之和为1，∴t+b=1-（18+38）=16．又6（X）=18×1+t×6+b×3+38×4=3，两式联立解得t=18，b=38．随机变量的方差是 18×（1-3）6+18×（6-3）6+38×（3-3）6+38×（4-3）6=1故答案为：1．
