--- I apologize for not being able to join you for dinner.
--- ______.

--Do you mind if I smoke here?

   --____________.

A. Sure. Go ahead     B. No. Go ahead     C. Yes. Please

—Jack, could I use your laptop for a while?

—___________. Go ahead, please.

A．With pleasure      B．No way           C．By all means       D．Come on

—I have to invite a professional hand to approach it.

—________ Your neighbor is an expert at all.

A．Go ahead.         B．That’s settled.     C．What for?         D．Why bother?

—Shall I lock the lab now before I go home?

  —_____. I’ll check it myself later.

       A．Go ahead  B．No problem     C．All right   D．Don’t bother