Someone is ringing the doorbell. Go and see ___________.
| A．who is he | B．who he is | C．who is it | D．who it is |
The children, ________ had played the whole day long, were worn out.
| A．all of what | B．all of which | C．all of them | D．all of whom |
We are confident that the environment ________ by our further efforts to reduce pollution.
| A．improves | B．will be improved | C．has improved | D．was improved |
— Where did you find the professor who made the speech yesterday?
— It was in the hall_______ the students often have a meeting.
| A．where | B．which | C．that | D．when |
When I first met Mary I didn’t like her, but I ________ my mind.
| A．have changed | B．change | C．had changed | D．would change |
I ________ myself more— it was a perfect day.
| A．shouldn’t have enjoyed | B．needn’t have enjoyed |
| C．wouldn’t have enjoyed | D．couldn’t have enjoyed |