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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

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Modal verbs with have 2

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Comments

--> 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,

Kirk

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?

Thanks.

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: https://learnenglish.britishcouncil.org/grammar/intermediate-to-upper-intermediate/modals-deductions-about-the-past

Best wishes,

Jonathan

The LearnEnglish Team

Hello

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.

 

Peter

The LearnEnglish Team

Thanks for your detailed and prompt reply!

I have a feeling that "must" conveys the idea of conclusion and is often used in explanations, whereas "will" is more about assumption or expectation.

That is why I think it would be better to say "Dear Sir, You will recently have received a form", which gives a sense that the sender is assuming that the recipient of this email has received a form, rather than drawing a conclusion from some evidence.

Similarly, for "We sent the invitations on Monday, so they will have received them by now". If "must" were used instead, it would convey a slightly different meaning, conveying a sense that the speaker has some evidence to support his conclusion.

Is my understanding of the difference correct?

Thanks teacher.

Hello Sunyoung1005,

Yes, that's right.

With the second sentence, must is possible because the evidence could be a knowledge of how the postal service works, but will is also fine.

 

Peter

The LearnEnglish Team

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