—You were brave enough to shout at the meeting.
—Well, now I regret _____ that.
| A．to do | B．to be doing |
| C．to have done | D．having done |
Has ________ been decided when we are to hold the sports meeting?
| A．that | B．he |
| C．it | D．what |
—Who knocked at the door?
—I’ve no idea. I just pretended nobody was at home, so I didn’t ask who ________ was.
| A．he | B．that |
| C．she | D．it |
The doctor kept telling him that he mustn’t smoke, but ________ didn’t help.
| A．he | B．which |
| C．it | D．they |
Don’t leave your keys in the car. Someone might steal ________ 。
| A．one | B．that |
| C．this | D．it |
Computers must be of great use to ________ doing the scientific research.
| A．these | B．whoever |
| C．those | D．whomever |