Task 1
1. -, -
2. -, -
3. the
4. the, -, -, the
5. the, the, -
6. -, the, the
7. the
8. -
Task 2
1. If people were not waste paper, many trees would be saved.
2. Our environment would be safer, if people protected it every day.
3. If she read the environmental research yesterday, she would get a better mark on biology.
4. If we started to take care of wildlife, we would save many species of animals and plants.
5. If I were you, I would never drop litter in the streets.
Task 3 (не уверена, что всё правильно)
1. Jane had phoned Mom at work before she left for Moscow.
2. When we got married I had known Jack for 2 years.
3. When Heather opened her windows the sun had already sat.
4. Last year Susan passed all her tests and exams.
5. I knew him when I was at school.
6. I have never been to the USA. I wanted to go there last summer but I couldn't.
7. Have you heard the news? Our neighbors have moved to Germany.
8. It has been very foggy since morning today.
9. What were they do when you saw them?
10. When she saw him a year ago she didn't recognize him.
11. It was raining heavily when he went out.