----May we leave the classroom now?----No you . You to leave until the bell rings.A. must

问题补充：

----May we leave the classroom now?

----No, you . You to leave until the bell rings.

A. mustn’t; are allowed

B. can’t; aren’t allowed

C. don’t have to; are allowed

D. needn’t; aren’t allowed

答案：

A. mustn’t; are allowed

(答案→)B. can’t; aren’t allowed

C. don’t have to; are allowed

D. needn’t; aren’t allowed

解析：固定句型结构may I+动词原形表示我能不能做某事，表示的是一种请求，肯定性回答常用can，否定性回答常用mustn’t或can 来回答。故选B。