LI Na1, SHEN Jin2, JI Shuang3, LU Zheng-Zheng2, GAO Xin-Yue2, WEI Rui3**, CHEN Ying4
1. Beijing Zhongguancun Middle School,Beijing 100086,China; 2. Department of Education,Beijing Normal University,Beijing 100875,China; 3. College of Chemistry,Beijing Normal University,Beijing 100875,China; 4. Beijing Haidian Teachers Training College,Beijing 100195,China