—Do you mind if I smoke here?
—______ I feel a bit sick.
| A．Not at all. | B．Why not. |
| C．Go ahead. | D．I’d rather you didn’t. |
We must not touch this switch under any ______.
| A．situation | B．atmosphere |
| C．circumstances | D．civilization |
I had written twice to Janet. But she didn't ______ my letters, so I decided to go there myself.
| A．return | B．reply | C．answer | D．receive |
You've ______ a zero in this phone number, so you can't get through.
| A．left out | B．broken out |
| C．put out | D．got out |
He did not regret saying what he did but felt that he ______ it differently.
| A．could express | B．would express |
| C．could have expressed | D．must have expressed |
--You didn't wait for Tom yesterday.
--Yes, but we ______. He didn't come.
| A．needn't have | B．didn't need to |
| C．could have | D．should have |