参考资料http://www.baidu.com/s?ie=gb2312&bs=%B9%ED%CD%B7%CC%EC%B1%F8+bt%CF%C2%D4%D8&sr=&z=&cl=3&f=8&wd=%B9%ED%CD%B7%CC%EC%B1%F8%CF%C2%D4%D8&ct=0
