You phone him if you want to but you ! He will surely phone you.A. may; mustn’tB. have t

问题补充：

You phone him if you want to, but you ! He will surely phone you.

A. may; mustn’t

B. have to; needn’t

C. can; needn’t

D. can; doesn’t need

答案：

A. may; mustn’t

B. have to; needn’t

(答案→)C. can; needn’t

D. can; doesn’t need

解析：表示“你可以”用you may或you can都正确，B项肯定不对，关键还是need的用法，根据下文He will surely phone you soon，可知“你没必要”，因此排除A，mustn’t“不许；禁止”，语气不对，D错在主谓搭配不一致。