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8. If he polished his shoes, he would look smart.
9. If he could park near his office, he would come by car.
10. If the flats were clearly numbered, it would not be difficult to find anyone.
11. If I knew her email address, I could tell you.
12. If she didn't work in the evening, she would have time to play with her children.
13. If I were tall enough, I could join the basketball team.
14. If Peter prepared his lessons well, he wouldn't get bad marks.
15. If you don't go right now, you will be late for the train.
16. If we don't hurry up, we will be late for the exam.
17. If you often talked to them, they would understand you. 
18. Should I know the correct answer, I will tell you.
19. Were the weather nice, we would go on a picnic.