David apologized for ______ to inform me of the change in the plan.
| A．his being not able | B．him not to be able |
| C． his not being able | D．him to he not able |
—Excuse me!
—________.
—Could you tell me how I can get to the first department?
| A．Pardon? | B．Why? | C．Yes? | D．Please. |
—Shall I lock the lab now before I go home?
—________.I'll check it myself later.
| A．Go ahead | B．No problem |
| C．No hurry | D．Don't bother |
—Can I ask you a rather personal question?
—________
| A．Thanks，take it easy. | B．Thanks，help yourself. |
| C．Of course，go ahead. | D．Of course，why not? |
—I had a great time in the summer holidays.We went scuba－diving in Hawaii.
—Wow！________
| A．I'm going to Hawaii，too. |
| B．How generous you are! |
| C．That sounds really cool! |
| D．Enjoy yourself! |
—Thank you very much for helping me with the luggage.
—________.
| A．Don't say so | B．With pleasure |
| C．I'd love to | D．Not at all |