http://www.17edu.com/dili/HTML/17217.html
http://zhidao.baidu.com/question/165131.html看看这里吧
http://cache.baidu.com/c?word=%B4%BA%BC%BE%3B%D0%C7%BF%D5%3B%CD%BC&url=http%3A//www%2Ewen8%2Enet/science/geo/xingktu/&b=0&a=2&user=baidu