This document discusses various past modal verbs in English including: should have/should not have, may have/may not have, might have/might not have, will have/will not have, would have/would not have, could have/could not have, must have/must not have. It provides examples and explanations of the meanings and uses of each modal in the past tense, such as expressing regret with should have, possibility with may/might have, and probability with must have.

1. PAST MODALS

2. CAN
SHOULD HAVE/SHOULD NOT HAVE
MAY HAVE/MAY NOT HAVE
MIGHT HAVE/MIGHT NOT HAVE
WILL HAVE/WILL NOT HAVE
WOULD HAVE/WOULD NOT HAVE
COULD HAVE/COULD NOT HAVE
MUST HAVE/MUST NOT HAVE
SHALL

3. SHOULD HAVE AND
SHOULD NOT HAVE

4. Should have = it didn’t happen in the past, and that
was a mistake. “Should have” expresses regret.
I didn’t do very well on the test. I should have
studied harder.
I should have invited him. = I didn’t invite him, and
I feel bad.
I should have gotten everyone’s approval. = I didn’t
get everyone’s approval, and I regret that.

5. Should not have = it did happen in the past, and
that was a mistake. “Should not have” also
expresses regret.
He should not have married her. = He married her,
but it was a mistake.
You shouldn’t have been there. = You were there,
and that was a mistake.
I shouldn’t have decided to take 18 units this
semester. (But I did, and it’s too hard.)

6. MAY HAVE AND MAY NOT
HAVE

7. “May have” is maybe in the past tense.
He missed the meeting. He may have
forgotten. He may have been sick. He
may have been too busy. He may have
gotten stuck in traffic.
All these are things that maybe
happened in the past.

8. “May not have” is maybe not in the past
tense.
He missed the meeting. He may not
have known about it. He may not have
had time.
=
Maybe he didn’t know about it. Maybe
he didn’t have time.

9. MIGHT HAVE AND MIGHT
NOT HAVE

10. MIGHT HAVE = MAY HAVE
MIGHT NOT HAVE = MAY NOT
HAVE
DON’T WORRY ABOUT ANY
DIFFERENCE IN THE MEANING.

11. WILL HAVE AND WILL
NOT HAVE

12. “Will have” is THE FUTURE PERFECT for something
that will happen in the future, before something else
further in the future.
In 2020, I will have graduated from Laney.
(I will graduate before 2020.)
By November, we will have studied the passive voice.
(We will study the passive voice in October.)
By November, we will have taken the midterm.
I will not have finished this work by this evening.
(I won’t finish before this evening.)

13. WOULD HAVE AND
WOULD NOT HAVE

14. “Would have” is for the past unreal conditional.
If they had offered me more money, I would have
taken the job. = They didn’t offer me more money,
and I didn’t take the job. I didn’t take the job
because they didn’t offer me enough money.
If I had had a good job in my country, I would no have
come here. = I didn’t have a good job, so I came to
the U.S.

15. “Would not have” is for the past unreal conditional.
If he had been wearing his seat belt, he would not
have been hurt. = He got hurt because he wasn’t
wearing his seat belt.
If she had known about his drinking problem, she
would not married him. = She married him. She didn’t
know about his drinking problem. Now she knows and
is sorry.

16. COULD AND COULDN’T

17. “COULD” is the past tense of can.
“COULDN’T is the past tense of can’t.
I couldn’t sleep last night because I was
worried about my.
I could swim when I was seven years old.

18. COULD is used for polite requests.
Could you open the window, please?
Could I be your partner?
Could you give me a ride.
(In these situations, you can also use “would”
with the same meaning, or “can,” which is
less polite.)

19. “How could you do this to me?” = an
accusation that you did something bad.
I don’t understand how I could end up with
you,
I don’t understand why she could say a thing
like that.
(In all these situations, something bad
happened in the past.

20. COULD HAVE AND
COULD NOT HAVE

21. “Could have” is for something that was
possible in the past, but did not happen.
I could have gotten married when I was 19,
but I decided not to. It was not the right
time.
He could have gotten killed in that accident
if he hadn’t been wearing his seat belt.
Be careful! You could have hit me!

22. “Could not have” is for something that
was not possible in the past.
I could not have helped him even if he
had asked me. (It wasn’t possible for me
to help him.)

23. “Couldn’t” and “could not have been” can be
used to mean “I don’t believe it.”
She couldn’t be sixty years old. She only
looks 45.
A: I saw you at school yesterday.
B: That couldn’t have been me. I wasn’t here
yesterday.

24. MUST HAVE AND
MUST NOT HAVE

25. “Must have” = I think that something
probably was true in the past.
Must not have” = I think that something
probably was NOT true in the past.
(Note that this is a completely different
meaning from “must” = You must do your
homework. The past tense of that must is
always had to– I couldn’t go out because I
had to do my homework.)

26. “Must have” = I think that something
probably was true in the past.
I can’t find my reading glasses. I must
have left them in my office = I think that
probably I left them in my office.
He missed the meeting yesterday = He
must have been sick.

27. Must not have” = I think that something
probably was NOT true in the past.
He didn’t answer his phone. He must not
have had turned on.
He failed the class last semester. He
must not have studied hard.