Составить 10 условных предложений

Упражнение 18. Обрадуйте условные предложения.
11. It is late, and I have to go home. If ... . 12. I was expecting my friend to come, that's why I couldn't go to the cinema with you. If ... . 13. He always gets top marks in mathematics because it is his favourite subject and he works a lot at it. If ... . 14. I didn't translate the article yesterday because I had no dictionary. If ... . 15. We lost our way because the night was pitch-dark. If ... . 16. The box was so heavy that I couldn't carry it. That's why I took a taxi. If ... . Упражнение 19
Образуйте условные предложения.1. The travellers had no camera with them, so they could not take photos of the beautiful scenery. If ... . 2. There was no sugar left, so we had to go to the shop late in the evening. If ... . 3. This house is very nice and comfortable, but it is not very good for living because it is situated close to a chemical plant and the air around is very bad. If ... . 4. He is an excellent specialist, but I can't ask his advice because I'm not acquainted with him. If ... . 5. You cannot enjoy this merry evening party because you have a toothache. If ... 6. You know the material well enough, but you are very absent-minded, and that's why you always make many mistakes. If ... . 7. You did not ring me up, so I did not know you were in trouble. If .. . 8. You left the child alone in the room, so he hurt himself. If ... . 9. They spent a year in the tropics, so they got very sun-tanned. If ... . 10. It rained heavily, so we got drenched to the skin. If ... . 11. Why didn't you watch the cat? It ate all the fish. If ... . 12. A huge black cloud appeared from behind the forest, so we had to turn back and hurry home. If ... . 13. We shall not go to see them because it is very late. If ... . 14. Naturally she was angry, because you were in her way. If ... .