I can’t go to the cinema with you because I stay here until my mother comes back.A. canB.

问题补充：

I can’t go to the cinema with you because I stay here until my mother comes back.

A. can

B. could

C. may

D. must

答案：

A. can

B. could

C. may

(答案→)D. must

解析：本题的含义是我不能和你去电影院，因为我必须在这儿一直呆到我母亲回来，must表示必须的意思，故本题选D。