问题
选择题
—Listen! Helen is singing in the next room.
—It _______ be Helen. She has gone to Beijing.[ ]
A. can't
B. mustn't
C. may
D. should
答案
答案：A
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—Listen! Helen is singing in the next room.
—It _______ be Helen. She has gone to Beijing.[ ]
A. can't
B. mustn't
C. may
D. should
答案：A