— Can I go to the movie Mum?— Certainly. But you be back by ten o’clock.A. canB. mayC. m

问题补充：

— Can I go to the movie, Mum?

— Certainly. But you be back by ten o’clock.

A. can

B. may

C. might

D. must

答案：

A. can

B. may

C. might

(答案→)D. must

解析：根据句子的意思，母亲对于子女的要求，故选D