23. John waited at the bus-stop for nearly half an hour 　　　　　　the bus finally arrived .

　　　 A．when 　　　　　　　　 B．as 　　　　　　　　　　 C．before 　　　　　　　 D．while

22. Not that I’m unwilling to lend you a hand ,　　　　 　I’m too busy for the moment .

　　　 A．because 　 B．but that 　 C．but 　 D．however

21. Jack had traveled six miles across the Channel 　_____his engine failed and was forced to land on the sea .　　　

　　　 A．when 　　　　　　　　 B．until 　　　　　　　　　 C．after 　　　　　　　　　 D．since

20. _____ I know the money is safe, I shall not worry about it.

　 A. Even though　　　 B. Unless　　　 C. As long as　　　 D. While

19. -When did he leave the classroom?

　　　 -He left　　　 you turned back to write on the blackboard.

　　　 A．the minute　　　　　 B．the time　　　　　　　 C．until　　　　　　　　　 D．before

18.　　　 he thought he was helping us with the work, he was actually in the way.　　　　

　　　 A．Although　 B．Unless　　　 C．Because　　 D．When

17. Hearing his words ,I couldn’t decide 　　　　　or remain .

　　　 A．whether to go abroad 　　　　　　　　　　　　 B．if I go abroad

　　　 C．if to go abroad 　　　　　　　　　　　　　　　　　 D．to go abroad

16. Questions and exercises　 are given by the computer, which decides ______ to move the students ahead, review an easier level, ____ give more work on the same level.

　 A. either, or　　 B. both, and　　 .C. whether, or　　 D. not only, but also

15. -Will you go to Mary’s birthday party?

　 -No, ____ invited, I can’t go to it. I’ll be too busy then.

　 A. if　　　 B. unless　　 C. even though　　 D. when

14. The librarian promised to get the book for me ____she could remember who last borrowed it.

A. in case　　　　 B. if only　　　　 C. even if　　　 D. ever since