1. If you do not like this one, I'll bring you another

=>Unless.

2. If she does not hurry, she'll be late

=>Unless

3. If you are not careful, you'll cut yourself

=>Unless

4. If you had not sneezed, he wouldn't have known that we were there.

=> Unless

5. If you don't study harder, you 'll fail the next exam.

=> Unless

6. If he doesn't practice writing every day, he can't improve his writing skill.

=> Unless

7. Unless this man is a driver, he can't help you move by car.

=>If

8. Unless you go out more often, you might fall ill.

=>If

9. If you don't return this book to the library today, you'll have to pay a fine.

=> Unless

10. If he cleaned up the car now, his boss could ask him to do this.

=> Unless

11. Unless they were absent now, they would meet the headmaster.

=> If

12. If I didn't know the number, I would not ring her up.

=> Unless

13. If my sister had a terrible headache, she would be absent from her class.

=> Unless

14. If Peter didn't study hard, he could not get good marks.

=> Unless

15. Unless you drive more carefully, you will have an accident.

=> If

16. Unless you pure these trees, they won't grow well.

> If

17. If you practice your English, you can improve it quickly.

=> Unless

18. If you don't hurry, you'll be late for school again.

=> Unless

19. Unless there is oxygen, fire cannot burn.

=>If

20. If you go to bed late, you'll feel tired in the morning.

=> Unless

21. My parents will be angry unless I pass my exams.

=> If

22. She can't travel abroad if she doesn't have a passport.

=> Unless

23.Ba can't watch TV unless he finishes his homework.

=> If

24. Unless you had stayed at home yesterday, you wouldn't have enjoyed a delicious meal.

=>If

25. Unless he had been busy last night, he could have met his friends.