Решение:
- He washed his car last Saturday.
- He is washing his car at the moment.
- He often washes his car.
- We bought the chair a month ago.
- They made friends when they were little children.
- She is doing a grammar exercise now.
- She is a pupil. She often does grammar exercises.
- She did the exercise an hour ago.
- His grandfather worked at the circus when he was young.
- Don't ask him any questions now. He is working.
Ответ: 1. washed, 2. is washing, 3. washes, 4. bought, 5. made, were, 6. is doing, 7. does, 8. did, 9. worked, was, 10. is working.