The secretary worked late into the night, ______a long speech for the president.
| A．to prepare | B．preparing | C．prepared | D．was preparing |
We can't wait any longer ________ we'll miss the plane.
| A．or | B．but |
| C．so | D．yet |
House prices vary from place to place and are usually high ________ there are famous schools.
| A．when | B．since |
| C．where | D．whether |
It will be another 50 years ______ our country is expected to reach the level of a medium developed country.
| A．since | B．before |
| C．that | D．when |
Jerry has promised to keep the secret, so he won't tell anyone ________ asked to.
| A．until | B．now that |
| C．unless | D．even though |
The movie Life of Pi is so attractive that it holds the audience's curiosity ________ the story reaches the end.
| A．until | B．before |
| C．after | D．when |