可乐定属于
A．α-受体激动剂B．β-受体激动剂C．α-受体拮抗剂D．钙离子阻断剂E．ACEI
参考答案：A
You look that light-hearted. Nothing seems ________ to you.
A．to happen
B．to be happened
C．to have happened
D．to have been happened
散射线主要产生于（）
A.汤姆逊效应
B.光电效应
C.康普顿效应
D.电子对效应
E.光核效应
