CHEN Ying1, WANG Lei2, XU Min3, CHEN Song4, SHANG Rong-Rong4, NING Yan-Dan2
1. Beijing Haidian Teachers Training College, Beijing 100195, China;
2. College of Chemistry, Beijing Normal University, Beijing 100875, China;
3. Beijing Institute of Education Fengtai Branch, Beijing 100072;
4. Beijing Fengtai District Secondary School, Beijing 100071, China