— we clean the classroom at once? — No, you . You clean it after school.
A. Must; needn’t; may
B. Must; mustn’t; can.
C. Shall; can’t; must
D. Need; mustn’t; may
网友回答
(答案→)A. Must; needn’t; may
B. Must; mustn’t; can.
C. Shall; can’t; must
D. Need; mustn’t; may
解析：用must提问的句子的否定回答，一般用needn’t。所以可以排除其他选项，选a。