—Listen ! Helen is singing in the next room.—It be Helen. She is in Tianjin now.A. can’tB

问题补充：

—Listen ! Helen is singing in the next room.

—It be Helen. She is in Tianjin now.

A. can’t

B. mustn’t

C. may not

D. shouldn’t

答案：

(答案→)A. can’t

B. mustn’t

C. may not

D. shouldn’t

解析：根据后文的答语She is in Tianjin now，可作出推测，不可能是Helen，故选A