1. You have to leave now ______ you can catch the early bus.
A. so that B. as soon as C. because D. if
2. You should go over your test paper _____ you hand it in.
A. before B. though C. because D. as soon as
3. Scientists say it may be a few years ______ it is possible to test the new medicine on patients.
A. because B. after C. before D. since
4. We will have no water to drink ______ we don’t protect the earth.
A. until B. before C. though D. if
5. --- Could we play football in your playground, Sir?
--- No, _______ you have the principal’s note.
A. if B. unless C. because D. since
6. I won’t be able to understand what you say, ______ you speak too quickly.
A. if B. though C. because D. until
7. --- Is everybody here today?
--- No, Tom is at home ______ he has got a bad cold.
A. because B. if C. until D. unless
8. In summer, food goes bad easily _____ it is put in the refrigerator.
A. until B. if C. unless D. though
9. _______ it’s difficult to make her dream come true, she never gives up.
A. Though B. Until C. Unless D. If
10. --- I hear Jack will come to China next week.
--- Really? ________ he comes, my younger sister will be very happy.
A. If B. Until C. Unless D. Before
11. Mary spends a lot of money on clothes ________ her family is not rich.
A. because B. though C. if D. so
12. Usually, we don’t know how important something is ______ we lost it.
A. or B. until C. as soon as D. if