1. PAST POSSIBILITY

2. USE We use May have Could have Might have To discuss possibility.
You are not sure, so you are guessing.
If I had known about the test, I might have studied.
He may not have said anything because he was worried.

3. PRACTICE
With your partner, pick someone else in the classroom. Guess what they might have done last night!
________ may have _______
________ could have ________
________ might have ________

4. USE May have and might have are the same.
Could have cannot be used in the past!
He might not have seen you.
He couldn’t have seen you. INCORRECT

5. USE We use couldn’t have to show certainty!
A: I saw you cheat on your test yesterday!
B: What? That’s impossible! You couldn’t have seen me cheat! I wasn’t in class yesterday!

6. USE
You can discuss past probability (you are 60%- 100% sure) using must.
A: Why didn’t Matthew say anything to you?
B: He must not have heard me.
When you failed your first assignment, you must have been very worried!

7. USE Be careful – must does not mean necessity!
If we are talking about something you needed to do, use “had to”
When I got to school, I must have gone to class at 9:00.
When I got to school, I had to go to class at 9:00.

8. PRACTICE
With your partner, pick someone else in the classroom. Guess what they must have done yesterday! (You are quite sure, but not completely sure)
________ must have _________