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31. Unless you do exercises, you will be punished.
32. If the building weren't too high, he could climb up.
33. If that house weren't expensive, I could buy it.
34. If he had worked hard last term, he wouldn't have lost his job.
35. If Mary had had money with her, she could have bought that present.
36. If I had known that there was a test yesterday, I would have studied.
37. If I had known that my friend was in hospital, I would have visited her.
38. If I had known that you have never met my friend, I would have introduced you.
39. If it hadn't been cold yesterday, I would have gone for a walk.
40. If I weren't tired, I could cycle to work.
41. isn't it
42. don't you
43. does he
44. isn't she
45. isn't it