Modal verbs for speculation

1.

Modal verbs for speculation

2.

Reflections on possible situations
1)He could be a professor. I saw his class.
2)He could have been a teacher because he knows so much.

3.

Thinking about situations we're sure
of.
3)He must be here. He promised me.
4)He must have been here ten minutes ago because we had an
appointment.

4.

Thinking about situations in the
present.
5)He could be an actor because I think I've seen him somewhere
before.
6)He must be an actor. I've seen him in a movie.