到这里看看http://www.baidu.com/s?ie=gb2312&bs=%B1%B1%BE%A9%D3%D0%B6%E0%C9%D9%BC%D2%B7%BF%B5%D8%B2%FA%BE%AD%BC%CD%B9%AB%CB%BE&sr=&z=&wd=%B1%B1%BE%A9+%B5%D8%B2%FA%BE%AD%BC%CD%B9%AB%CB%BE&ct=0&cl=3&f=8
不太清楚啊,太多了
