18. If, as Mr Fox says, the repair turned out to be so complicated, they___ much earlier. But nobody expected it would be so time-consuming. A. should start
B. must have started
C. might start
D. ought to have started
19. If, indeed, you a police agent who was following you on the train, the situation may soon become very serious. A. had seen
B. saw
C. have seen
D. see
20. I know how much you dislike him, but when you meet him you should behave as if you ___ to your best friend
A. had been taking
B. would talk
C. were talking
D. talk
21. A model which___ all these requirements would cost at least a thousand pounds more, which means it would be too expensive for us anyway
A. would meet
B. will meet
C. meets
D. will have met
22. You are a smoker yourself, Mr Parker. How did you find out someone in your study?
A. had to be smoking
B. was smoking
C. has been smoking
D. had been smoking​