—Look! Somebody _____ the sofa.
—Well, it wasn’t me. I didn’t do it.
| A．is cleaning | B．was cleaning |
| C．has cleaned | D．had cleaned |
If _____ carefully, the experiment will be successful.
| A．do | B．does | C．done | D．doing |
He is a man of few words, and seldom speaks until _____ to.
| A．spoken | B．speaking | C．speak | D．be spoken |
There are five pairs, but I'm at a loss which _____ to buy.
| A．to be chosen | B．to choose from | C．to choose | D．for choosing |
He was not an actor, who often appeared on stage, _____ a writer, writing stories.
| A．but | B．and | C．then | D．so |
I don't know whether to stay in teaching or _____ another job.
| A．trying getting | B．to try to get | C．trying to get | D．try get |