Here are the completed sentences with the correct verb forms:

17. If we had known who he was, we **would have invited** him to speak at our meeting.
18. My dog **barks** if it **hears** any strange sound.
19. If I **had** enough money, I would buy a house.
20. They **would not let** you in if you **came** late.
21. If I **were** you, I **would accept** Mr. Anderson's invitation.
22. If I **won** a big prize in a lottery, I’d give up my job.
23. If I **told** you the truth.
24. I was busy. If I **had** free time, I **would go** to the cinema with you.
25. Why didn't you attend the meeting? Oh, I did not know. If I **had known**, I **would have come**.
26. What **would we do** if they do not come tomorrow?
27. If I had enough time now, I **would write** to my parents.
28. It's too bad Helen isn't here. If she **were** here, she **would know** what to do.
29. If I **eat** breakfast tomorrow morning, I **will get** hungry during class.
30. If she **comes** late again, she **will lose** her job.
31. I **will let** you know if I **find** out what's happening.
32. If we **lived** in a town, life would be better.
33. I'm sure he wouldn't mind if we **arrived** early.
34. We **will phone** you if we have time.
35. If I won the lottery, I **would give** you half the money.
36. It **would be** a pity if she married Fred.
37. If I’m free on Saturday, I **will go** to the mountains.
38. She **would have** a nervous breakdown if she goes on like this.
39. I know I **would feel** better if I **stopped** smoking.
40. If I **were** you, I **would help** him.
41. He didn’t listen to the teacher. If he **had listened** more carefully, he **would have performed** well in the examination.

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