问题补充:
----I’m sorry to have kept you waiting.
----
A. You are welcome
B. Go ahead
C. Don’t mention it
D. No problem
答案:
A. You are welcome
B. Go ahead
C. Don’t mention it
(答案→)D. No problem
解析:-I’m sorry的回答有No problem,it doesn’t matter,it’s ok,it’s all right,never mind