—It is said that Mike fought with Tom in class.

—It ______ be him. It is not ______ him to have done it like that. [ ]

A. can't; like

B. may not; as

C. can't; as

D. mustn't; like

计算题：有一台泵，有效功率为20千瓦，其轴需要的功率为22千瓦，试计算泵的效率。