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Modals with 'have'

Level: intermediate

We can use a modal verb with have and a past participle:

Subject Modal have Past participle  
They will have arrived by now.
You might have seen the film.
Jack and Jill would have been late.

We use a modal verb with have:

  • to refer back from the present:

It's nearly eight o'clock. They will have arrived by now.

  • to refer back from a point of time in the past:

We were very worried. We thought someone might have taken the car.

  • to refer back from a point of time in the future:

We won't eat until they arrive. They might not have had supper.

  • to refer to past time:

You should have helped her when she asked.
They might have got lost. Nobody knows where they are.

Modal verbs with have 1


Modal verbs with have 2




Hi team,
"Everyone ___ have a birth certificate. However, you didn't have to have one until about 100 years ago."
Teacher, I think blank is -has to- as rule.But answer key says -must-Is there a mistake?

Hi Nuro,

Both forms are possible here. I don't believe this is a question from our site so you'd have to ask the author why the key allows only 'must'.



The LearnEnglish Team

--> We could have borrowed the money (= it would have been possible for us to borrow the money) -- Is "might have" possible?

--> He might have called earlier, but I was not home. -- Does "could have" or "may have" have the same meaning in this context?

--> The criminal might not have been caught, had you not sounded the alarm. -- I understand that "could not have" is not possible here because it would mean impossibility. How about "may not"?

Thank you in advance teachers!

Hello AsahiYo20,

You could use 'might have', but it would express probability (a guess) instead of possibility. As you note, 'could have' expresses that you had the possibility of borrowing it, but 'might have' would express the idea perhaps you would have borrowed it (if, for example, the circumstances had been different).

'may have' means the same thing as 'might have' here. 'could have' can also be used to make guesses about the past, and thus could also be used here, but most of the time we use 'might have' or 'may have' to do this.

Yes, 'could not have' would express impossibility here. 'may not' would mean the same as 'might have'.

All the best,


The LearnEnglish Team

Hi Sir,

The decision could not have been easy.

They could not have guessed what was going to happen.

He can’t have done it deliberately.

In the sentences above, are "could" and "can" interchangeable?


Q1: Whether both "cannot have +p.p." and "could not have +p.p." are the opposite of must have +p.p.? In other words, whether either of them can be used when the speaker is sure that something did not happen?

Q2: In making a guess about something that happened in the past without knowing that whether it was true or not, are "might have + p.p." and "could have +p.p." interchangeable. In other words, could "could" in the following two sentences be replaced with "might"?

He could have got stuck in traffic.
He could have forgotten that we were meeting today.

Thanks in advance for answering my questions:)

Hi AkiraTa05,

Good questions. I'll try to answer below.

Q1: yes! Both can't have and couldn't have are the opposite of must have, for the meaning of deduction.

Q2: yes. You could replace could with might in those sentences.

You might like to have a look at this page, for more examples:

Best wishes,


The LearnEnglish Team


What is the difference between will have + p.p. and must have + p.p.? Are they interchangeable in the following sentences?

You must have been delighted when you head you had won the lottery

Dear Sir, You will recently have received a form

We sent the invitations on Monday, so they will have received them by now

Thanks in advance.

Hello Sunyoung1005,

Will have is an expression of belief. Must have is similar, but it is generally used when we have evidence of some kind (including past experience) which causes us to form an expectation. Must have carries a sense that the speaker would be surprised if things were not as he or she expects.


I think you could use will have in the first sentence, though must have is better as it carries the sense of I would be amazed if not.

Must have does not work in the second sentence as the context suggests that the writer sent the form. You could use must have if there were a time reference so the speaker could express an expectation that the time has been sufficient.

Must have is possible in the third sentence for the reasons above.



The LearnEnglish Team