Practice 1 OPEN CLOZE

1. No one knows how he died, but one theory is that it ................. have been a tragic accident.

2. The potato crops may have ...................... destroyed by insects.3. Scientists have many theories about what might .............. causing global

warming.4. When zoologists measured the spiders, they realised that they

must .............been at least 16cm in length.5. I should have .................. homework more often when I was at school.6. It is not true that the Great Wall of China can ....................... seen from the

moon.

Practice 2 : KEY TRANSFORMATION

7. I'm sure he didn't understand what I was saying to him.8. He what I was saying to him.

(misunderstood)9. It's possible that he missed his train.10.He his train. (might)11.It was very wrong of you to borrow my car without asking.12.You my car without asking. (have)13.Maybe Tom is looking for a new place to live.14.Tom for a new place to live. (could)15.Why aren't you at home revising for your exam?16.You for your exam at home now. (be)17.He looks really disappointed. Obviously he expected to win the race. (must)18.He looks really disappointed. He to win the race.