31．We were swimming in the lake _______ suddenly the storm started. (Beijing 2004 spring)
A. when B. while C. until D. before
30. _____ modeling business is by no means easy to get into, the good model will always be in demand. A. While B. Since C. As D. I (2004 Zhejiang)
29. Several weeks had gone by ______I realized the painting was missing.(NMET2004-4)
A. as B. before C. since D. when
27. Roses need special care _____ they can live through winter. (NMET2004-1) A. because B. so that C. even if D. as 28. _____you call me to say you' re not coming, I'll see you at the theatre.(NMET2004-2) A. Though B. Whether C. Until D. Unless
26. You can eat food free in my restaurant ____ you like. (Chongqinog 2004)
A. whenever B. wherever C. whatever D. however
25. Don’t be afraid of asking for help ____ it is needed. (NMET2003)
A. unless B. since C. although D. when
24. -Was his father very strict with him when he was at school? -Yes. He had never praised him_____ he became one of the top students in his grade. (2003Spring)
A. after B. unless C. until D. when
23. _______ I know the money is safe, I shall not worry about it. (2003Beijing)
A. Even though B. Unless C. As long as D. While
22. He made a mistake, but then he corrected the situation _______ it got worse.
A. until B. when C. before D. as (2003Beijing)
21. Mr. Hall understands that ___ math has always been easy for him, it is not easy for the students. (2003Anhui)