Who saw it ______ at that time?
| A．happen | B．happened | C．happens | D．to happen |
More and more people have realized that we won’t have cleaner water to drink unless something _______soon.
| A．is done | B．was done | C．will be done | D．to be done |
We have to ____the sports meeting till next Friday because of the bad weather
| A．put up | B．put away | C．put on | D．put off |
They are talking about the movie __they watched yesterday
| A．/ | B．whose | C．what | D．whom |
_____interesting work it is to teach children！
| A．How | B．What | C．What an | D．How an |