13. You will be late if you (not hurry) _________ don't hurry.

• This is a first conditional sentence, so we use the present simple in the if-clause.

14. Unless she (study) _________ studies, she will fail the final exam.

• "Unless" means "if...not," so we use the present simple in the if-clause.

15. We (go) _________ will go out if the rain (stop) _________ stops.

• This is a first conditional sentence.

16. If people (use) _________ used the car all the time, they (make) _________ would make the air dirty.

• This is a second conditional sentence, so we use the past simple in the if-clause and "would + base verb" in the main clause.

17. If we (not, waste) _________ didn't waste so much paper, a lot of trees (save) _________ would be saved.

• This is a second conditional sentence.

18. You (remember) _________ Do you remember all the answers if you're more patient?

• This is a question in the present simple.

19. If you see someone throw trash in the class, what (you do) _________ will you do?

• This is a first conditional question.

20. If people plant more trees, the air (not, pollute) _________ won't be polluted.

• This is a first conditional sentence (negative).

21. If today (be) _________ is Sunday, the students (not go) _________ won't go to school.

• This is a first conditional sentence.

22. If Hoan (be) _________ is 5 years younger, he (look) _________ would look for another job.

• This is a second conditional sentence.

23. They (travel) _________ would travel around the world if they (have) _________ had enough money now.

• This is a second conditional sentence.

24. If each water (be) _________ were your happiness, I (give) _________ would give you all the oceans in the world.

• This is a second conditional sentence (note: "were" is used for all subjects in the if-clause of a second conditional).

25. I (grow) _________ would grow trees everywhere on this planet if each leaf (be) _________ were your happiness.

• This is a second conditional sentence.

26. If paper (be) _________ were money, I (buy) _________ would buy you anything you like.

• This is a second conditional sentence.

27. If Diep (have) _________ had Lan's phone number, he (phone) _________ would phone her right away.

• This is a second conditional sentence.

28. I (stop) _________ would stop loving you if the earth (stop) _________ stopped moving around the sun.

• This is a second conditional sentence.

29. If I (be) _________ were the president now, I (give) _________ would give more jobs for the unemployment.

• This is a second conditional sentence.

30. If I (live) _________ lived in New York now, I (invite) _________ would invite Donald Trump a cup of coffee.

• This is a second conditional sentence