If I had more time, I would study harder for my exams.
If we had a bigger house, we would invite more friends over.
If I would have a car, I would drive to work.
If she was a teacher, she would help students.
If I had a car, I would drive to work.
If she were a teacher, she would help students.
A: In formal English, 'were' is preferred for all subjects in the second conditional.
A: Yes, it describes situations that are unlikely or impossible.