— Where is John? — He _____ in the library.
| A．should be | B．must be | C．can be | D．must have been |
The research showed beyond that smoking contributes to heart disease．
| A．reach | B．power | C．doubt | D．problem |
That art center is ____ used to be a factory,_____ millions of cars were made．
| A．what; which | B．where; where | C．what; where | D．where; which |
—Are you going to help him?
—Why ___ I help him? He' s never done anything for me．
| A．would | B．could | C．might | D．should |
The captain determined to be with the ship forever and never to disappointment even when the ship sank．
| A．gave way | B．gave over | C．gave off | D．gave up |
It is said that the old pot ____under the earth for about 1000 years by the time it was discovered.
| A．had buried | B．had been buried | C．buried | D．were buried |