.---John, how did your English exam go?
---I thought I ____, but in fact I came in the top 10% in the class.
| A．should have failed | B．couldn’ t have failed |
| C．might have failed | D．mustn’ t have failed |
31. ______ I really don’t like art, I find his work impressive.
| A．As | B．Since | C．If | D．While |
30. He was told that it would be at least three more months ______ he could recover and return to work.
| A．when | B．before | C．since | D．that |
29. The field research will take Joan and Paul about five months; it will be a long time ______ we meet them again.
| A．after | B．before | C．since | D．when |
28.“When did he leave the classroom?” “He left _______ you turned back to write on the blackboard.”
| A．the time | B．the moment | C．until | D．since |
27. “Shall Mary come and play computer games?”
“No, _______ she has finished her homework.”
| A．when | B．since | C．unless | D．as soon as |