问题补充：
—Thanks a lot, but can you do me one more favor, please?
—, sir. What can I do for you?
A. Just a minute
B. It’s very nice of you
C. At your service
D. Not a bit
答案：
A. Just a minute
B. It’s very nice of you
(答案→)C. At your service
D. Not a bit
解析：考察交际用语。A请稍等；B你真是太好了。C乐意为你服务；D一点也不；句意：—多谢，你能再帮我一个忙吗？—乐意为你服务。我能为你做什么？根据句意说明C正确。
