.
I remember putting the tape recorder in the corner, but what _______ it?
| A．has happened on | B．has become of | C．has happened | D．has taken |
I’ll go and see you whenever _______.
| A．you are convenient | B．it will be convenient to you |
| C．at your convenience | D．it is convenient for you |
— How about the suggestion Prof. Smith put forward at the meeting last Friday?
— The committee discussed it for hours without a decision _______.
| A．taking | B．to take | C．being taken | D．taken |
The poor man, ______, ran out of the dark cave.
| A．trembling and frightened | B．trembled and frightening |
| C．trembled and frightened | D．trembling and frightening |
On Christmas Eve, we put up some balloons to _______ the festival atmosphere.
| A．make for | B．add to | C．add up | D．join in |
We went to forbidden City last month, ______, not surprisingly, was crowded with visitors.
| A．that | B．where | C．which | D．when |