This exercise about past modals (modal verbs used to talk about the past) is part of a complete Upper-Intermediate English Course (B2 CEFR level). If you need to revise what these verbs are, check out this lesson on modal verbs in our intermediate course or this lesson about question formation with modal verbs in our elementary course. There are various interactive grammar exercises for past modals.
Let’s have a look at how to speculate about the past using modal verbs or past modals. This guide is divided into 4 parts. There are a variety of interactive exercises at the end of the guide.
When I was younger, I wasn’t a great student and looking back, I think that I should have worked a bit harder at school. If I had worked harder I might have got better results. In reality, I got decent results in my exams, so I can’t have been a terrible student and must have understood the material quite well!”
Perhaps you recognize some of the verbs in that quote. “Should”, “must”, “can’t” and “might” are all modal verbs but are used here to speculate about the past.
If I say “I should study” I am talking about what I think would be a good idea now, as we use “should” to make recommendations or describe what we are supposed to do.
If I say that “I should have studied” I am talking about what would have been a good idea for me to do or what I was supposed to have done in the past.
This is how we use modal verbs to speculate or talk about the past, we always combine;
Modal Verb + Have + Past Participle
There are various modal verbs that we use in this way, we can use “Should / ought to”, “Must” “May / Might / Could” & “Can’t”.
|When you are sure of something.
|If you aren’t sure of something (speculation).
|When you are sure that something is impossible.
|If you are making recommendations about the past.
|Must + have + participle
|May / Might / Could + have + Participle
|Can’t + have + participle
|Should / ought to + have+ participle.
|“Tom’s car isn’t here, he must have gone out.”
|“He might have gone to the supermarket.”
|“He can’t have gone to work, it’s Saturday.”
|“He should have told me if he was going out!”
When we are talking about the past and we are sure of something, we can use must have followed by a past participle.
For example, if you bought some milk yesterday and now there is none left, you could think that
Someone must have drunk it.
or if you parked your car somewhere and when you get back it has gone, you could speculate that
Someone must have stolen my car!
If we are not sure about something in the past, but we have an idea or think that something was a possibility, we can use might have, may have or could have.
If I put my hand in my pocket and can’t find my wallet, I could speculate that someone stole it.
Someone might have stolen my wallet!
or maybe I just left it at home.
I might have left my wallet at home.
Or perhaps I left it in a shop.
I could have left my wallet in the shop.
In this context, may, might and could are synonymous.
If you are sure that something in the past was not possible, you can use can’t have.
For example, If I ask my friend to come to the premier of a film with me, but they say that they have seen the film before, I could say that
You can’t have seen the film before, it was only released today, this is the premier!
Or if someone says that they saw me in the street yesterday, but I was at home all day, I could reply that
You cab’t have seen me in the street yesterday, I was at home all day!
We can use should to make suggestions. When we are talking about the past we can use should + have + past participle.
For example, if I failed a test because I hadn’t studied, I would probably think
I should have studied!
Or if I forget an important phone number, I might think
I should have written it down!
So, if I am in my apartment and can’t find my keys, I can logically say that
” I must have had my keys when I came home or I wouldn’t have been able to open the door!”
This means that I can be quite certain that I had my keys, or it would have been impossible to get into the flat.
Similarly, If I am thinking about where I left my keys, I can speculate by saying
“I may have left my keys in my jacket pocket, or I might have left them on the table by the door, or I could have left them in my trouser pocket.”
However, If I am sure that it is impossible that I lost my keys outside the apartment I can say
“I can’t have lost my keys at the pub because I used them to open the door when I came home last night.”
Similarly, I could also tell myself what I should have done (what would have been a good idea) by saying
“I should have put my keys in the bowl by the door, then I wouldn’t have this problem now!”
Test yourself with the quizzes below, each one practices a different aspect of the grammar.