http://www.baidu.com/s?ct=0&ie=gb2312&bs=%D0%C2%BE%F8%B4%FA%CB%AB%BD%BF&sr=&z=&wd=%BF%AA%B9%FA%B4%F3%B5%E4%BD%CC%B0%B8&cl=3&f=8 随便都能搜到啊
让同学先分段,再1段1段的讲
