We believe scientists will a way to solve the problem of air pollution.
A. set off B. put off
C. come up with D. catch up with
You had better _____ home at once . Don’t keep your mother _____ .
A.to…wait B.going…waiting
C.to go…to wait D.go…waiting
Remember ______ the book in time when you have finished _____ it .
A. to return…reading B. returning…reading
C. returning…to read D.to return…to read
It will about half an hour to get to the zoo by bus.
A. spend B. take C. pay D. cost
Tom, together with his parents the yard when I saw him.
A. is cleaning B. was cleaning
C. are cleaning D. were cleaning
---What are you going to do this afternoon?
---I’m not sure. I go swimming with my friend.
A. may B. can
C. may be D. must
