The students _______ busily when Miss Brown went to get a book she _______ in the office.
| A．had written, left | B．were writing, has left | C．had written, had left | D．were writing, had left |
I’m sorry you’ve been waiting for so long, but it’ll still be some time _______ Brian gets back.
| A．since | B．after | C．when | D．before |
My glasses，________I was like a blind man, fell to the ground and broke.
| A．which | B．with which | C．without that | D．without which |
The computer system________suddenly while he was searching for information on the Internet.
| A．broke down | B．broke out | C．broke up | D．broke in |
With ______ help of WWF, many endangered species are now enjoying a peaceful life in ______ wild.
| A．/; the | B．the; the | C．the; / | D．/; / |
The plan was so shallow and impractical that no serious _________was ever made to realize it.
| A．recognition | B．comment | C．attempt | D．credit |