—Listen！Helen is singing in the next room.
—It be Helen .She has gone to Beijing.
A. should
B. mustn’t
C. may
D. can’t
网友回答
A. should
B. mustn’t
C. may
(答案→)D. can’t
解析：A. should 应该 B. mustn’t 禁止 C. may可能 D. can’t不可能；句意：听！海伦正在隔壁房间唱歌。不可能是海伦，她已经去北京了。故选D