1. If I knew your address, I could write you a letter.
2. If I had a house in the city, I wouldn't live in a countryside.
3. Unless you start early,you will miss the train.
4. If she had known my phone number, she would have called me last night.
5. If it hadn't rained heavily, they wouldn't have cancelled the trip.
6. If he didn't eat too much, he wouldn't been overweight.
7. If they didn't leave the door open, the room wouldn't been cold
8. If she doesn't work hard, she will fail she next exam.
9. I would buy a bicycle if I had enough money.
10. Had you listened to me, you wouldn't have got into so much trouble.