+ | | | | | | | + | A A | | | B | A | + | | | C C | | D D | D | D | | D | + | | 40 ~75 | 2~3 25 | | + | | | 300 | 2 1 | 40 ~75 40 ~75 | 30 | | | | http://mongol.people.com.cn/15830920.html |