在有机物分子中，若碳原子连接四个不同的原子或原子团，该碳原子称为不对称碳原子（或手性碳原子），以*C表示．具有手性碳原子的有机物具有光学活性．

— There's          wrong with my chair. Can you mend it?
— No problem. 

    Most of my day is full of lessons and homework. It is very1to find time for myself. But when I get some2time, I have many3to do, such as sleeping, going to the movies and listening to music. First, I4sleeping very much. When I am at school, I try to make time during my5 and lunchtime to get a few minutes to sleep. It helps me6awake all the way. If I do not get a good sleep, I will be very7the next day. Second, going to the movies can make me relaxed. When I am8, it is9a good idea to go out and watch a movie. Laughing, getting frightened and even10are all good ways of relaxing.

    Listening to music is my hobby11. I think music is very important in everyone's life. Some parents think listening to music will make their children become12students, so they13them from listening to it. But I don't think so. When I am in a bad mood（心情）, music can14me quiet.

    15 hobbies, there will be no color in my life. I will keep my hobbies forever.