20. It’s high time that we （采取措施）to stop pollution.(take)
21. （要花费她很长时间）to recover from the illness.(take)
22. This/It is the third time that I .（see）
（到长城）.（be）
24. It is / has been two years （自从他出国）.（go）
25. whether I like it or not，because you never listen to me.（make）
26. （用不了多久）before we know the result of the experiment.（be）
27. Measures have been taken to solve the problem，but 过段时间）before the situation improves.（some）
28. （没关系）the weather was bad.（matter）
29. （是否要紧）whether we go together or separately?（matter）
30. （我突然想起）that he might have forgotten our date.（occur）
31. he will change his mind.（chance）
32. （很可能）we will go to Beijing.（chance）
33. （似乎有）hundreds of people in the field；it was quite full.（seem）
34. （曾经有）a church at the corner of the street.（be）
35. She she had nothing to do with the decision.（make）
36. I everything is ready.（see）
37. What a pity my new computer doesn’t work. 问题）with it.（wrong）
38. （结果）she was a friend of my sister.（turn）
39. Come and see me when .（convenient）
40. complaining . It doesn’t make difference.（point）