LI Fang-Fang1, ZHANG Feng-Jie2, BU Qing-Jun3, LI Ying4, ZHANG Rui-Lin1, HU Jiu-Hua1**
1. College of Chemistry, Beijing Normal University, Beijing 100875, China; 2. Shandong Provincial Academy of Educational Recruitment and Examination, Ji'nan 250011, China; 3. Weifang Institute of Education Sciences, Weifang 261041, China; 4. Weifang No.1 Middle School, Weifang 261205, China