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Modals – deductions about the present

Do you know how to use modal verbs to say how certain you are about a possibility?

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

Intermediate: B1


If a sentence says "I missed the school bus. I must or might be late for school?"

Hello Oliver Goldwyn,

In this context you are speculating about the future so the correct choice is might.



The LearnEnglish Team

Today I learned the big difference between modal verbs that useful daily, I love with learning English every time... thanks for your support...

Hello The LearnEnglish Team,
Would you please explain me difference between two sentences below?
1.Do not call them now. They must be sleeping.
2.Do not call them now. They can be sleeping now.

Hello BobMux,

To be honest, neither of these sound natural to me, but if I were to use one of them, I'd use 1. If I don't know whether they are sleeping or not, but think that they probably are, I'd say 'Don't call them now. They're probably sleeping' (or perhaps 'They might be sleeping').

I'd use 'they must be sleeping' if, for example, I called them but they didn't answer the phone.

I can't think of a situation when I'd use 'can' here.

All the best,


The LearnEnglish Team

Hi team,
I am confused about this sentence:''Snacks can taste be sweet or salty''Why we use -be-?
''Snacks can taste sweet or salty.''Isn't true?

Hi Yigido,

That sentence is not correct. As you say, we do not use 'be' here. You could say either of these:

Snacks can taste sweet or salty.

Snacks can be sweet or salty.

I'm not sure, but I think 'savoury' may be a better word here than salty. It would depend on the context, of course.



The LearnEnglish Team

Thank you teacher.

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.

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