If or Unless?

Choose unless or if to complete these sentences

1. we don't leave now, we will miss the plane
   1. Unless
   2. If
2. I will give you a present,
   you get good marks
   1. unless
   2. if
3. Our gardener won't cut the grass
   it rains tomorrow
   1. unless
   2. if
4. I will forget to post the letter
   you don't remind me
   1. if
   2. unless
5. I will call the police
   they don't stop fighting
   1. if
   2. unless
6. we do the homework, our teacher will be pleased
   1. Unless
   2. If
7. their friends don't have a spare room, they will stay in a hotel
   1. Unless
   2. If
8. you don't exercise, you will get fat
   1. Unless
   2. If
9. she doesn't apologise, I will never speak to her again
   1. If
   2. Unless
10. she comes home soon, we will have dinner together
    1. Unless
    2. If
11. you tidy your room, I won't take you to the party
    1. If
    2. Unless
12. he goes to bed now, he'll be tired tomorrow
    1. Unless
    2. If
13. you hurry, we will be late for school
    1. If
    2. Unless
14. you hurry, you won't arrive on time
    1. Unless
    2. If
15. it rains, we will go camping
    1. Unless
    2. If
16. she books the tickets, she won't go to the concert
    1. Unless
    2. If
17. she eats less, she won't lose any weight
    1. Unless
    2. If
18. We won't go on holiday
    we can take our dog with us
    1. unless
    2. if
19. She will go for a walk
    it rains
    1. if
    2. unless