________ from heart trouble for years，Professor White has to take some medicine with him wherever he goes.
| A．Suffered | B．Suffering | C．Having suffered | D．Being suffered |
- Mr. White, will you please teach me how to perform pair skating today?
-- . You have to practise single skating well first.
| A．Two heads are better than one. | B．Think twice before you do. |
| C．Learn to walk before you run. | D．One today is worth two tomorrows. |
________ there is no restriction on foreign entries at the film festival ，those that win are in minority.
A. unless B. When C Where D while
________ seems to be a strong competition in China for senior high students to enter college or university.
| A．It | B．This | C．That | D．There |
It is no use _________ to persuade him ________ smoking because he has been addicted to it since he was young.
| A．trying, to quit | B．to try, to quit | C．to try, quit | D．trying, quit |
I would have come earlier, but I ________ that you were waiting for me.
| A．hadn’t known | B．didn’t know | C．would have known | D．haven’t know |