1. He might have agoraphobia.
2. He can’t be serious. He must be joking.
3. The doctor can’t have told him to stay at home for so long.
4. Someone must be taking care of him.
5. He might be suffering from severe depression.
6. He can’t have the use of his legs.
7. He must have a serious illness.
8. He must be overweight.
9. He could be afraid of people.