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 (59 votes)

Hello juniar,

I think the difference between expectation and speculation is merely the speaker's certainty. Expectation suggests that the speaker thinks something is likely; speculation less. Since must already suggests a high degress of confidence I think expectation or strong belief is a better description.

Note that your sentences do not use must in this way. We use must to speculate about the present, not the future. Your sentences describe a future situation. You could say something like this:

It's 6pm. He must be here.



The LearnEnglish Team

Hello caroluska,

We often use may when describing what is acceptable or allowed within rules, particularly the rules of a game or sport. It's a form of permission: you are allowed to do this by the rules.

You can read more about this on these pages:



The LearnEnglish Team

Submitted by Evgeny N on Mon, 03/02/2020 - 09:42

Dear teachers! In Grammar test 1 we have the next sentence: Come and sit down. You must be tired after the journey Could you tell me please is it possible to use might instead of must? I understood that must, in this case, it's opinion of this person offering to sit down. But isn't it sound a slightly rude and could we use might to make it sound more polite?

Hello Evgeny N,

Grammatically, might is posssible. However, it does not fit the context.

In this sentence must is not a command or an instruction. It is a deduction. It means that the speaker has good reason to believe something and is often used to mean 'I can see that...'.

For example, if someone arrives at my house and I can see that they are wet then I might say 'It must be raining'. I could draw other conclusions, too, such as 'You must be cold'.


We use might in a similar way when we are speculating and are not sure if we are correct. For example, if I try to phone my friend and there is no answer then I could say 'His phone might be turned off' or 'He might be in a meeting'.



The LearnEnglish Team