Modals in Past

Number 44 of 75 in C1/2 - ADVANCED+

New English word? Translate any word using double click.

Today we are going to have a look at how to use the Modals in the Past. Grammatically it is fairly simple, but you will have to be aware of certain differences of tone. First, let’s have a look at what I consider to be Modal verbs.

A Modal Verb has only one form. It cannot be used with a Gerund (…, nor does it use an ‘..s’ for the third person singular. Except for ‘OUGHT TO’ it is not followed by a preposition. This is the full list:


MUST  n’t 




I have not included NEEDN’T, HAVE TO or HAD BETTER. ‘Have to’, which uses the auxiliary ‘DO’ is NOT a Modal Verb with this definition (There is no ‘correct’ definition of a Modal Verb. As a teacher I prefer the definition which helps students to understand). Click here if you would like a full explanation. 

How to put a Modal Verb in Past

This is the easy part! This is the formula:


You could have warned me!
James must have arrived
It can’t have been easy

As is logical, in a question the Subject and the Modal are inverted:

We should have come earlier
Should we have come earlier?


It is not possible to say ‘CAN HAVE DONE’ something, but it is possible to say ‘CAN’T HAVE DONE’ something.

It is not possible to say ‘MUSTN’T HAVE DONE’ something, but it is possible to say ‘MUST HAVE DONE’ something.

It is not possible to use SHALL with a Past meaning.

If you want to use OUGHT TO instead of SHOULD, the structure is: ‘The weather OUGHT (not) TO HAVE been a problem’.

Could, Might, Can’t and Must

COULD is used in the same sense as it is in the Present, but with a sense of Past action:
‘Keep your eyes on the road!! You could have killed me!’
‘Nottingham Forest dominated the match from the first minute – It could have been 5 – 0.’

‘Could’ is in itself a Modal with a Past meaning, but notice the difference, which is similar to Spanish:
I could read when I was 4.
I could have read a book, but I was too nervous to concentrate.

‘Might’ is very similar. It is used when a native Spanish speaker would say:
(‘Where’s Juan?’)
‘I don’t know. Perhaps he went to the dentist.’
This is grammatically correct, but a native English speaker would say:
‘I don’t know. He might have gone to the dentist.’
PERHAPS + PAST = MIGHT HAVE + Past Participle

‘May have..’ is identical to ‘Might have…’, but much more formal. It is not so commonly used, and it does not have the sense of permission (‘May I come in?’) that exists in the present:
The company may have underestimated the difficulties present in many emerging markets.

‘Can’t have…’ and ‘Must have’ are suppositions. They do not have the sense of ability or obligation that they do in the present:
‘Who was that man who spent the whole party dancing with Sarah? I didn’t see him very well.’
‘It must have been Simon’s brother – we don’t know him because he lives in Scotland.’
‘No – it can’t have been, because Sarah can’t stand Simon. I don’t think she’d dance with his brother.’

MUST HAVE is a stronger way of saying MIGHT HAVE. You are more certain of what you are saying.
‘The dog’s ill. He might have eaten some rat poison.’ (Possibility)
‘The dog’s ill. He must have eaten some rat poison.’ (Strong Probability)

In the same way, CAN’T HAVE is a stronger version of MIGHT NOT HAVE:
‘Man might not have landed on the moon. I’ve heard it was filmed in a Hollywood studio.’ (Some doubt)
‘Man can’t have landed on the moon. The technology at that time made it impossible.’ (Strong Improbability)

Third Conditional: Would

Changing a sentence from ‘would + Infinitive’ to ‘would have + Past Participle’ (In other words, from 2nd to 3rd Conditional) is to pass a Hypothetical Sentence from Present to Past:

I would(n’t) visit my uncle in Alaska  → I would(n’t) have visited my uncle in Alaska

You will have to know how to use the rest of the sentence:

If the company gave me my Christmas bonus, I would(n’t) visit my uncle in Alaska  → If the company had given me my Christmas bonus, I would(n’t) have visited my uncle in Alaska

For the full explanation of Conditionals (including the Third), click here. 

Future Perfect: Will and Won’t

This is easy to understand if you translate it directly into Spanish. Basically you imagine yourself in a future moment looking back into the Past (from that perspective, still the future now):

‘Today is Monday. I have to finish my project this week. I’m sure I will have finished before Friday.’
‘I will start University next year. I will have graduated from High School by then.’
‘When I get home tomorrow, I’ll start cleaning and preparing dinner – My wife won’t have had time to do anything before going to work.’
Should have vs. Had to vs. Must have

Finally, there is a way of speaking in Spanish that still confuses me, and differs from everyday use of English. In Spanish, people oten say: ‘Juan tenía que ir al medico’ or ‘Juan tenía que haber ido al medico’ or ‘Juan tuvo que ir al medico’. I’m never sure what this means exactly. Let’s look at three possibilities in English:

‘Juan should have gone to the doctor. He was coughing all night, but he refuses to to go!’
(He didn’t go)

‘Where’s Juan?’ -‘He had to go to the doctor.’     Remember that ‘have to’ is not a Modal Verb.
(He went)

‘Juan hasn’t come to work today. Do you know where he is?’ -‘He must have gone to the doctor. He was coughing yesterday.’
(You are supposing)

Ready for the questions? If you need more practice, there’s a Mini-Class on the same theme.