—What are you doing, John? Why stop?
—To be on the safe side, we’d fill up the car now for we _______ run out of gas on the way．
| A．must | B．will | C．might | D．should |
Not until he questioned the manager several times ___________ that the engineer-in-chief had gone to an important meeting.
| A．did he tell | B．he told | C．was he told | D．he was told |
Staff are allowed to take a ten-minute break every two hours to relax, use the bathroom or do ___________ else is necessary.
| A．something | B．anything | C．whatever | D．what |
Every solid object ______ reflect a sound，varying according to the size and nature of the object．
| A．must | B．shall | C．will | D．should |
I would be happier if you did more studying while you are free, but you ___________.
| A．don’t | B．didn’t | C．wouldn’t | D．weren’t |
The temperature on the inside of the car can be adjusted to suit the driver’s__________ in winter and summer.
| A．pleasure | B．preference | C．measurement | D．selection |