1. May, might, could, and must + have
Vanessa Rivera

2. Perfect Modals could have... may have... might have... must have...
Used to give possible reasons why something happened or didn’t happen in the past.

3. How do we use it?
Example: the street was wet when I got up. It must have rained last night. (I am almost certain it rained) S
Subject V
Verb PP M+
have
We use: May-Might-Could and Must + have + Past Participle to talk about degrees of certainty in the past.

4. Modals verbs in the past
Modals in Past
Would have
Could have
Might have
Should have
May have
Must have
Past Participle

5. MODAL + HAVE + verb in past participle
Modals in the Past
They are modals referred to actions that happened in the past
It must have been a difficult decision
They should have invited her to their wedding
MODAL + HAVE + verb in past participle

6. Modals in Past : Modal + have + past participle
Concept
Example
Must have
We are almost certain that was true
I am almost certain that you called – you must have called me last night
Could have
When we are not sure
I can´t find my book – I could have left it at work
May (not) have
We may have passed the test, but it was in French
Might (not)have
You might have sold the house, if you really needed the money
Must not have
Could not have
When we are almost certain that something was NOT true
He does not have a camera- he couldn´t have taken a picture.

7. Part 1 May (not) have . . . Might (not) have . . . Could have . . .
*used to give possible explanations for past events (not sure that it was true)
examples:

8. Why didn’t John come out to lunch with us yesterday?
I’m not sure.
He might have had too much work to do.
He may have been busy at work.
He could have gone to a meeting.

9. Why was Tomas late to class on Monday?
I’m not sure.
He might have woken up late.
He may have missed the bus.
He could have forgotten to set his alarm clock.

10. What do you think your husband got you for your anniversary?
I don’t know.
He might have gotten me some jewelry.
He may have bought me a new kitchen appliance.
He could have picked out some perfume for me.

11. I wonder why the teacher wasn’t in class on Friday.
He may have been sick.
He might have gone rock climbing.
He might have decided to take a relaxing day off.
these are all possible explanations

12. Part 2 Must have . . . *stronger than (almost 100% sure it was true)
-may have
-might have
-could have
examples:

13. Meaning / Use: Must have = similar to the use of may/might/could have…
Must have shows more certainty than may/might/could have…
Use must have + past participle to show a strong probability

14. Comparison: may/might/could have… versus must have…
John wasn’t in class today. I wonder why . . .
He could have been sick. OR
He may not have felt well.
He must have been sick. OR
He must not have felt well.
*here, we are more certain!

15. Did you see how well Sam played during the soccer game
Did you see how well Sam played during the soccer game? I was really surprised that he scored 4 goals because he usually doesn’t play that well.
He must have practiced a lot before the game. OR
He must have been practicing a lot recently.
(progressive form)

16. Part 3 Must not have . . . Could not have . . . examples:
(almost 100% sure it was NOT true)
examples:

17. *this is what we think PROBABLY happened
Jan looks really tired today. It’s strange to see her this way because she is usually very energetic.
She must not have gotten very much sleep last night.
*this is what we think PROBABLY happened

18. Negative Examples:
Richard’s wife bought a new table 2 weeks ago, but Richard still hasn’t assembled it.
I wonder why?
He must NOT have understood the instructions.

19. Structure: How to make this grammar
May
Might
Could
Must
past
participle +
HAVE +

20. For the NEGATIVE:
May
Might
Could
Must
past
participle +
NOT HAVE +

21. Now it’s YOUR turn!
What do you think? What are some possible reasons why these things happened? Write them on a piece of paper and show your writing to your teacher.

22. I wonder why Janet didn’t come to school today?
I wonder why Lisa and her husband decided to move to London.
3. I wonder what my mother got me for my birthday.