1. Keep silent or you'll wake the baby up.

=> If

2. Stop talking or you won't understand the lesson. => if you

3. Peter is fat because he eats so many chips. => If Peter

4. She is is lazy so she can't pass the exam. If

5. I didn't see the film last night, so I can't tell you now.

=> If I

6. He didn't revise all his lessons, so he failed the exam. => Had

7. If you arrive at the office earlier than I do, please turn on the air-conditioner. => Should.

8. The car breaks down so often because you don't take good care of it.

=> Were I

9. She got married at such an early age. Otherwise, she would be at university now. => Had

10. We won't go out unless it stops raining.

=> If