You ________ wait for him. I’m not sure whether he’ll come back or not today.
A. can’t B. shouldn’tC. mustn’t D. needn’t
—Why do you look so tired?
—Because we ________ for three hours without stopping.
A. work B. worked
C. have worked D. were working
We won’t start the meeting ________ the teacher arrives.
A. though B. until C. while D. and
The workers are trying to ________ what’s wrong with the machine.
A. look for B. care for C. find out D. take out
Internet is ________ used by people, especially by young people.
A. deeply B. widely C. hardly D. highly
It’s so fine. Why not ________ outdoors?
A. play B. plays C. playing D. to play
