http://baike.baidu.com/view/2380706.htm
http://image.baidu.com/i?ct=503316480&z=0&tn=baiduimagedetail&word=%B4%F3%D5%A2%D0%B7+%BF%A8%CD%A8&in=23245&cl=2&cm=1&sc=0&lm=-1&pn=6&rn=1&di=2634835480&ln=51&fr=
http://image.baidu.com/i?ct=503316480&z=0&tn=baiduimagedetail&word=%B4%F3%D5%A2%D0%B7+%BF%A8%CD%A8&in=5348&cl=2&cm=1&sc=0&lm=-1&pn=8&rn=1&di=860666680&ln=51&fr=
如图1，2，3 自己再创造下~
