Ответ:

1) If you send this letter now, she will receive it tomorrow

2) If I do this test, I will improve my English

3) If I find your ring, I will give it back to you

4) Peggy will go shopping if she has time in the afternoon

5) Simon will go to London next week if he gets a cheap flight

6) If her boyfriend doesn't phone her today, she will leave him

7) If they don't study harder, they will not pass the exam

8) If it rains tomorrow, I won't have to water the plants

9) You won't be able to sleep if you watch this scary film

10) Susan could not move to the new house if it isn't ready on time