问题补充：
---Thanks for your help, but can you do me one more favor, please?
--- , sir. What’s it then?
A. Just a minute
B. At your service
C. That’s right
D. It’s my pleasure
答案：
A. Just a minute
(答案→)B. At your service
C. That’s right
D. It’s my pleasure
解析：考查交际用语。A请稍等；B乐意为你服务；C那是对的；D我的荣幸。句意：—谢谢你的帮助。我还想你帮我一个忙。—乐意为你服务。请问：是什么忙呢？根据句意说明B正确，
