Put the verb in the correct form.

1. Columbus discovered America. 2. He has recovered well from his accident. 3. He did a lot of experiments last week. 4. He came home and realized that he had forgotten his keys. 5. I saw him yesterday. 6. When he came home, she had been experimenting with the dinner for two hours. 7. I forgot to call Jean yesterday. 8. Your room is still very messy. I asked you to tidy up two days ago. 9. I discovered that the meeting had been canceled. 10. They were playing football yesterday at 5 o'clock. 11. My room was very messy and my mum told me to clean it. 12. When she came home, he had been practicing for two hours. 13. She took him home yesterday at noon. 14. Jane helped me with my homework yesterday. 15. It was a very harmful experiment.