Поставьте глагол-сказуемое предложения в Past Simple Tense (прошедшее простое время), употребляя модальные глаголы can, may, must и их эквиваленты:

1. He may be in the garden, collecting flowers.
2. I can do this experiment myself.
3. You must study biology at the university.

пожалуууууйста((((

1. He might be in the garden, collecting flowers.

2. I could do this experiment myself.

3. You had to study biology at the university.