问题描述:
问题解答:
http://www.sxufe.edu.cn/yuanxi/yjs/train_goal/lygl.htmhttp://www.baidu.com/s?ie=gb2312&bs=%BB%A4%CA%D6%CB%AA&sr=&z=&wd=%C2%C3%D3%CE%B9%DC%C0%ED%D1%A7%D1%D0%BE%BF%C9%FA&ct=0&cl=3&f=8