The modal verbs are can, could, may, might, mustshall, should, will and would.

The modals are used to show that we believe something is certain, probable or possible:

Possibility:

We use the modals could, might and may to show that something is possible in the future, but not certain:

They might come later. (= Perhaps/Maybe they will come later.)
They may come by car. (= Perhaps/Maybe they will come by car.)
If we don’t hurry we could be late. (= Perhaps/Maybe we will be late)

We use could have, might have and may have to show that something was possible now or at some time in the past:

It’s ten o’clock. They might have arrived now.
They could have arrived hours ago.

We use the modal can to make general statements about what is possible:

It can be very cold in winter. (= It is sometimes very cold in winter)
You can easily lose your way in the dark. (= People often lose their way in the dark)

We use the modal could as the past tense of can:

It could be very cold in winter. (= Sometimes it was very cold in winter.)
You could lose your way in the dark. (= People often lost their way in the dark)

Impossibility:

We use the negative can’t or cannot to show that something is impossible:

That can’t be true.
You cannot be serious.

We use couldn’t/could not to talk about the past:

We knew it could not be true.
He was obviously joking. He could not be serious.

Probability:

We use the modal must to show we are sure something to be true and we have reasons for our belief:

It’s getting dark. It must be quite late.
You haven’t eaten all day. You must be hungry.

We use must have for the past:

They hadn’t eaten all day. They must have been hungry.
You look happy. You must have heard the good news.

We use the modal should to suggest that something is true or will be true in the future, and to show you have reasons for your suggestion:

Ask Miranda. She should know.
It's nearly six o'clock. They should arrive soon.

We use should have to talk about the past:

It's nearly eleven o'clock. They should have arrived by now.

Exercise

Section: 

Comments

Thank you very much for the explanation. Really appreciated, you guys are legends!

Hello,
I've come across the phrase "I wouldn't know" and looking it up I' ve found out that it can mean two things:
1)I couldn't say, when you haven't experienced something
2) How am I supposed to know?, when you are not the right person to answer a question/comment.

Is that correct?

Thank you.

Hello Knightrider,

I think that's a good summary. The communicative meaning of the phrase is very much dependent on the context, so it's important to look at how it is used in context, not in isolation.

 

Best wishes,

Peter

The LearnEnglish Team

Hello Peter,

Yes absolutely. Context is all-important to distinguish the two meanings. I just wanted to be sure that I have grasped both senses. Thanks again

Regards.

Hi!
How can you differentiate between ability, possibility, probability and obligation in the sentence below?
´´Every person has particular ways to do things that may seem strange to others´´.
Thank you!

Hello girlbah,

One way you could do it is by using other words or phrases instead of 'may'. For example, 'be able to' for ability, 'it is possible' for possibility, 'it is likely' for probability and 'must' or 'should' for obligation.

Which one makes the most sense to you here?

All the best,
Kirk
The LearnEnglish Team

Whats the meanning of "vicious dog"?
Thanks

Hello Wolframio,

The phrase is 'a pretty vicious dog'. 'Pretty' here means 'quite' or 'fairly'.

You can find the meaning of 'vicious' in any online dictionary - see here, for example.

 

Best wishes,

Peter

The LearnEnglish Team

Good day !

what tense is `must have been´ ?

Hello mgfielrocha,

In 'must have been', 'have been' is a perfect infinitive, which in this case is used to speak about the past, but as far as I know there is no name for the tense in this form. This is because 'must' and most modals don't really have tenses -- we have to use other words to express the same idea in a different time. For example, to speak about past obligation, we have to use 'had to' instead of 'must'.

If you're interested in learning more about this, the Wikipedia English modal verbs page would be a good place to start.

All the best,
Kirk
The LearnEnglish Team

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