Ответ:

17. 1. returned home

2. found

3. phoned me; left

4. arrived; bought

5. said; has already met

6. remembered;  hasn't told

7. put; fell

8. began; entered

9. switched off; went

10. have eaten; returned

21. 1. came; was cooking

2. were choosing ; saw; was speaking

3. was writing

4. was dusting; vacuumed

5. turned off; locked

6. returned; were sleeping

7.  was getting dark; left

8. were you doing; phoned; was preparing;

9. was... riding; met

10. did...finish; was reading; finished

Объяснение: