No such authorization ______ be given without the president’s written permission.
| A．should | B．shall | C．would | D．may |
When he was alive, the old scientist used to say that knowledge ______ from practice and he gained his experience by doing a lot of practical work.
| A．was coming | B．had come |
| C．comes | D．would come |
He ______ articles for our wall-newspaper these three years, and he ______ about forty articles.
| A．has been writing; has written |
| B．has been writing; wrote |
| C．is writing; has been writing |
| D．has written; has written |
--- ______ Betty this morning?
--- Not yet, but she is sure to be here before noon.
| A．Have you seen | B．Will you see |
| C．Do you see | D．Did you see? |
--- Is Tom still smoking?
--- No. By next Saturday he ______ for a whole month without smoking a single cigarette.
| A．will be | B．will have gone |
| C．will have been | D．has been going |
The vegetables didn’t taste very good. They ______ too long.
| A．had been cooked | B．were cooked |
| C．have cooked | D．cooked |