Polar bears live mostly on______ sea ice, which they use as ______platform for hunting seals.
| A．a; a | B．a; the | C．不填; a | D．the; 不填 |
Mr. Smith couldn’t open the door because his naughty boy ______ it from the inside.
| A．would lock | B．was locking | C．has locked | D．had locked |
We’re advised not to leave the water ______ after using it.
| A．run | B．running | C．to run | D．having run |
She ______ have attended that meeting, for she was doing paperwork in the office then.
| A．shouldn’t | B．mustn’t | C．wouldn’t | D．couldn’t |
I know little about the accident because not much ______ about it up to now.
| A．has said | B．has been said | C．had said | D．had been said |
______ the task in time, we had to work late into the night.
| A．Finished | B．Finishing | C．To finish | D．Having finished |