人造石的主要成分不包括（）.
A.α－半水硫酸钙
B.β－半水硫酸钙
C.二水硫酸钙
D.无水硫酸钙
E.生石膏
参考答案：B, C, D, E
Tom was late for school ___________________, which, of course, made his teacher very angry.
A．more or less
B．sooner or later
C．here and there
D．over and over again
理解监督功能
