— Listen! Someone is singing in the music room. It ______ be Jim. He practices singing there every day.

— It ______ be him. He has gone to Beijing. [ ]

A. can; can't

B. must; may not

C. must; can't

D. may; may not

某专业分包单位根据施工总承包商的委托，承担工程中的基坑支护工程施工，由于设计单位提交的基坑支护设计考虑不周导致基坑出现坍塌事故，该事故的责任方是( )

A．项目法人
B．施工总承包商
C．专业分包单位
D．监理单位
E．设计单位