--- 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 |
--- 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 |