Jawaban:

1.mercury will freeze if the temperature falls below -38.83

2. if she signed the contract, i would be very happy

3.if i knew they were eating, i met them another day

4. A balloon rises if it is filled with hot air

5. if the sun shines, I go to school

6. if i was at school i would be studying right now

7. if you didn't remind me, i might forgotten

8. what will i do if she doesn't come?

9. i wish i booked the hotel in advance

10. i wish she wasn't here now

11. he wishes he will win the competition tomorrow

12. if i didn't missed that train , i wouldn't be late now

13. if i were you, i would returned those books

14. if kim were here now, she would know how to launch this

15.if she looked at the locator, she wouldn't be lost now

16. if i were you, i would tell my teacher all yesterday's story

17. if i knew the truth I would told you already

18. i wished i didn't tell him a single word about this

19. if i have enough money, i would have fixed my old car

20. if i hadn't met her, i wouldn't knew how lovely she was