---Listen!Davidistalkinghappilywithhismotherinthenextro...

问题详情：

--- Listen! David is talking happily with his mother in the next room.

--- It ______ be his mother. She has gone to Yunnan to be a volunteer doctor.

A. should                 B. must                       C. can’t                      D. mustn’t.

【回答】

C

知识点：情态动词

题型：选择题