Here are conditional sentences based on the situations provided:

13. If you had told me you were online, I would have sent you an email.

14. If the church bells didn’t keep me from sleeping, I would get more rest.

15. If you eat lots of vegetables and fruit, you will maintain a healthy weight.

16. If you leave now, I will never speak to you again.

17. If the boy were older, he could go to school.

18. If you press that button, the machine will stop working.

19. If you want him to come, why don’t you invite him to your birthday party?

20. If it weren’t so windy, we could go sailing.

21. If you don’t stop following me, I will call the police.

22. If you are not calm, you will make a wrong decision.

23. If she hadn’t been so shy, she wouldn’t have hidden behind her mother.

24. If she had a visa, she could have come to that country.

25. If there were no plants, animals would have no oxygen to breathe.

26. If Tom didn’t have a big house, we couldn’t stay at his house.

27. If he didn’t work in the garden, he wouldn’t be so tired.

28. If he were more confident, he could perform on stage.

29. If she didn’t have many friends, she would get bored.