—Look! The lights in the teachers' offic
问题:
—Look! The lights in the teachers' office are still on. Is Mr. Li working?
—No. It _______ be Mr. Li. I saw him leave just now. [ ]
A. may not
B. mustn't
C. can't
D. needn't
—Look! The lights in the teachers' office are still on. Is Mr. Li working?
—No. It _______ be Mr. Li. I saw him leave just now. [ ]
A. may not
B. mustn't
C. can't
D. needn't