-----Mr. Smith, can I e to ask for some advice on my paper at any time?
-----Yes, of course. .
A. If you’re convenient
B. At your convenience
C. That’s right
D. Don’t mention it
网友回答
A. If you’re convenient
(答案→)B. At your convenience
C. That’s right
D. Don’t mention it
解析：考查交际用语的使用。 At your convenient在你方便的时候。A项表达错误，convenient主语不可能是人。根据语境，B项正确。