1)I didn't know that Joe had to get up early, so didn't wake him up. If I knew he had to get up early, I'd wake him up.
2) I was able to buy the car only because Jane lent me the money. If Jane didn't lend me the money, I wouldn't be able to buy the car.
3) Karen wasn't injured in the crash because she was wearing a seat belt. If Karen didn't wear a seat belt, she would be injured in the crash.
6) You didn't have any breakfast that's why you're hungry now. If you had some breakfast, you wouldn't be hungry.
7)I didn't get a taxi because I didn't have any money. If had some money, I would get a taxi.