Ответ:1.If I meet him, I'll give him back his book.

2.Unless you exercise regularly, you won't be able to keep fit.

3.If you exercise regularly, you'll keep fit.

4.If you wear a warm jacket, you will not feel cold.

5.Unless you put on a warm jacket, you will feel cold.

6.If you are too tired, let's not go for a walk.

7.I won't do it unless you agree to help me; I'm not doing it alone.

8.We'll be in trouble unless he helps us.

9.Hurry up! Unless you start now, you will not get there in time.

10.If we hurry, we'll arrive on time.

11.I'll be back home tomorrow unless there is a flight delay.

12.If you don't stop making that noise, I'll call the police.

13.Unless you want to come with us, we'll leave without you.

14.Don't say that again unless it's an emergency.

15.If you say that again, I'll get furious.

16.Unless you use new words many times, you will not remember them.

17.Let's stay at home if you are so tired.

18.Let's not go for a walk if you're tired and would like to stay in.

19.I won't order beefsteaks for us if you're a vegetarian.

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