4. If I hadn't felt tired, I could play football this afternoon.
5. If Olga and Ivan had been paying attention, they would have seen the sign marking their exit from the highway
6. If she had a college degree, she could be employed
7. If she hadn't walked to the meeting, she wouldn't have been late
8. If you don't promise to return back, I won't lend you
9. If the weather hadn't been terrible, we wouldn't have put off our trip
10. If Sally hadn't been absent from school on Friday, she would know what she has to do for homework
11. Unless you like this one, I'll bring you another
12. But for Martin's nerve, he wouldn't have failed the driving test last week
13. If he pays me tonight, I will have enough money to buy a car
14. If you don't leave me alone, I'll call the police
15. Should you arrive at the office earlier than I do, please turn on the air-conditioner
16. Had it not been for his early death, he would be a famous musician by now
17. Were I in your shoes, I would take good care of it
18. If you tell lies for your boss, you'll be fired at once
19. If he had revised all his lessons, he wouldn't have failed the exam