MOU Peng-Zhou1*, PU Yu1, YAN Lv-Wei1, CHEN Dong-Mei2, XI Chun-Hui3
1. Lixian Experimental Middle School, Longnan 742299, China; 2. College of Chemical Engineering and Technology, Tianshui Normal University, Tianshui 741001, China; 3. Lixian Education and Teaching Research Office, Longnan 742200, China