$△ABC$中，已知$a=x,b=2,B=60°$，如果△ABC$△ABC$ 两组解，则$x$的取值范围（    ）

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   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?
   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.
   The researchers also found the effect is greater on the younger people who learn a second language.
   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.
   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.
   “Our findings suggest that the structure of the brain is changed by the experience of learning a second language,” said the scientists.
It means that the change itself increases the ability to learn.
   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.”

在洋葱根尖细胞中，组成核酸的碱基、五碳糖、核苷酸各有几种（）

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    Do you feel lonely when your best friend isn't around? Of course, yes. Here's our advice to you—and to all kids who feel lonely sometimes. 
You may feel lonely at break or lunchtime when a best friend isn't around—maybe because he or she moved to a different school or a different class. You want to have new friends, but how do you make them? Maybe it seems everybody else already has his or her friends. But remember, there's always room for more friends.
    Start by looking around your classroom—think about which kids you'd like to play with at break. Look for chances to say hi to them, smile, and be friendly. Offer to share something or express your appreciation (欣赏) to them. Invite someone to play with you or say, “Do you want to sit here?” in the lunchroom. When you're at break, walk over to kids you want to play with, act friendly, and say “Hi, can I play, too?” or just join in. 
     If you have trouble doing this or if you're feeling shy, ask your teacher to help you make new friends. Teachers are usually pretty good at matching up friends. The best way to make friends is to be a friend. Be kind, be friendly, share, say nice things, offer to help ---and pretty soon, you'll have one, or two, or even more new friends.
    You might still miss that special best friend. But when you see each other, you can share something you didn't have before he or she left. You can introduce him or her to your new friends!