Modals: deductions about the present

Modals: deductions about the present

Do you know how to use modal verbs to say how certain you are about a possibility? Test what you know with interactive exercises and read the explanation to help you.

Look at these examples to see how must, might, may, could and can't can be used.

That must be the main entrance. I can see people queuing to get in.
I've lost my keys. They might be at work or they could be in the car.
You can't be bored already! You've only been here five minutes. 

Try this exercise to test your grammar.

Grammar test 1

Modals – deduction (present): Grammar test 1

Read the explanation to learn more.

Grammar explanation

We can use modal verbs for deduction – guessing if something is true using the available information. The modal verb we choose shows how certain we are about the possibility. This page focuses on making deductions about the present or future. 


We use must when we feel sure that something is true or it's the only realistic possibility.

This must be her house. I can see her car in the garage.
He must live near here because he always walks to work.
Come inside and get warm. You must be freezing out there!

might, may, could

We use might, may or could to say that we think something is possible but we're not sure. 

She's not here yet. She might be stuck in traffic.
He's not answering. He could be in class.
We regret to inform you that some services may be delayed due to the bad weather.

They all have the same meaning, but may is more formal than might and could.


We use can't when we feel sure that something is not possible.

It can't be far now. We've been driving for hours.
She can't know about the complaint. She's promoted him to team leader.
It can't be easy for him, looking after three kids on his own.

Note that these verbs, like all modal verbs, are followed by an infinitive without to.

Do this exercise to test your grammar again.

Grammar test 2

Modals – deduction (present): Grammar test 2

Language level

Average: 4.2 (58 votes)

Submitted by Basheer Ahmed on Thu, 30/07/2020 - 14:12

Hello sir, I found a confusing structure from a book "Practical English Usage by Michael Swan" for Modal verb 'MUST'; I am afraid we must be going. Can you help me clarify the progressive structure with the modal 'MUST', what is the purpose behind using the structure like that? Thank you.
Profile picture for user Kirk Moore

Submitted by Kirk Moore on Thu, 30/07/2020 - 14:57

In reply to by Basheer Ahmed


Hello Basheer Ahmed,

Modal verbs have several different uses and meanings. 'must' can be used to express not only deductions, but also obligations, that is, things we need to do.

As Swan explains in his section on different verb forms that can be used to express distancing (and thus make sentences more polite), continuous forms sound more temporary or developing, and so are more polite.

So this sentence is a more polite way of saying 'We must go'.

Hope this helps you make sense of it.

All the best,


The LearnEnglish Team

Hello Sir Kirk, Thank you very much. It is really helpful and helped me in understanding the complete purpose of the usage. Sir, from that topic I have one more question; what does it mean by "DISTANCING" that Michael Swan has put it down many times at different places in his book? Could you please make it clear with examples? Thank you.

Hello Basheer Ahmed,

If you have Swan's book, he explains this in his sections on politeness, but basically, this refers to different verb forms that we can use to put space between us and what we are talking about.

For example, instead of saying 'I need to go', I can say 'I need to be going' -- the continuous form instead of the bare infinitive suggests a temporary need, which can make my need to go sound like something imposed on me rather than my choice. Since it's not my choice, it's more 'distant' from me. In many other languages, this would probably sound ridiculous, but this is one important way in which English verb forms can be used to be more polite.

I hope this helps you make sense of it.

All the best,


The LearnEnglish Team

Profile picture for user Karan Narang

Submitted by Karan Narang on Fri, 10/07/2020 - 04:27

I could be there just minutes for having my breakfast even though I have a some work after working I may be there to having breakfast.

Submitted by Rsb on Tue, 05/05/2020 - 10:55

Sir, "Could have+ verb 3rd form" is also used for past possibility Guess about something in the past?? Example, Sachin could have played.
Profile picture for user Kirk Moore

Submitted by Kirk Moore on Tue, 05/05/2020 - 16:19

In reply to by Rsb


Hello Rsb

Yes, 'could have' + past participle can be used to speak about a past possibility (see the Intermediate level under Possibility and impossibility). 

All the best


The LearnEnglish Team

Profile picture for user OlaIELTS

Submitted by OlaIELTS on Sun, 03/05/2020 - 15:03

It's really interesting.

Submitted by juniar on Tue, 21/04/2020 - 05:22

How to distinguish between if I don't know they are different meaning: He must be here at 6pm (expectation) He must be here at 6 pm (speculation) Thank you