While watching television, ________.
| A．the doorbell rang | B．the doorbell was rung |
| C．we heard the doorbell ring | D．we heard the doorbell rings |
．________ all over the hills and around the lake are wild flowers of different kinds.
| A．To grow | B．Growing | C．Grown | D．Grow |
I think that this meal was well worth ________ was charged for it.
| A．that | B．what | C．which | D．how many |
—The experiment is of particular importance.
—I see. We will carry on with it ________ we can get enough money.
| A．unless | B．though | C．whether | D．until |
When people move to another country, they often try ________ the customs of their native land.
| A．to keep on | B．to keep off |
| C．to keep up | D．keeping up |
Working conditions in that company isfew clerks stay longer than three hours.
| A．such that | B．so that | C．that | D．what |