—Do you mind if I sit here sir?—. Please sit down.A. I’m sorry but I doB. Not at allC. O

问题补充：

—Do you mind if I sit here, sir?—. Please sit down.

A. I’m sorry, but I do

B. Not at all

C. Of course

D. Thanks a lot

答案：

A. I’m sorry, but I do

(答案→)B. Not at all

C. Of course

D. Thanks a lot

解析：I’m sorry, but I do抱歉，我介意；Not at all一点也不；Of course当然了；Thanks a lot多谢。句意：先生，你介意我坐在这儿吗？根据下文，请坐。可知选B，最符合语境。