The content is the finale of the senior high school entrance examination, and there are some variants of the finale of geometric functions, which are quite good. The previous explanation is that there are many solutions to one problem, and the problem set is a solution to many problems, and the analysis is very thick.

Duan is from Suqian, Jiangsu. He won the second prize of Jiangsu junior high school mathematics young teachers' basic skills competition and the first prize of Yangzhou junior high school mathematics proposition competition, and published many papers in magazines above the provincial level.