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

what are the usages of 'Must, must be, and must have been' please help me understand with at least one example for each ?

Hi Kirk
Thank you for answering my previous question . Please I have one more query.
I would go to the cinema , if I have the time.
Is the above sentence correct or should I say I would go to the cinema if I had the time.
Many thanks for your help

Hello sumanasc,

We would use 'had' here. Conditional forms are either about likely/possible events or unlikely/impossible events and we do not mix the two in one sentence. Therefore in your sentence we would either use 'will... have' (likely) or 'would... had' (unlikely).

 

Best wishes,

Peter

The LearnEnglish Team

Hi Kirk
Can you please tell me whether the sentence under modal verb " I could help you , if I find my car " is correct .
Many thanks

Hello sumanasc,

You could probably hear some people say 'I could help you if I find my car', or perhaps find it in writing, but the grammar is a little bit non-standard. This is because the sentence has one verb ('find') in a first conditional structure and the other verb ('could') in a second conditional structure. Please take a look at our Conditionals 1 page to see what I mean.

The sentence in full first conditional structure would be 'I can help you if I find my car' and in full second conditional structure would be 'I could help you if I found my car'.

All the best,
Kirk
The LearnEnglish Team

Hi there,
I have always tried to learn Modals but I find them really difficult!
We use could have to talk about possibility and about ability.
They could have arrived hours ago( did they arrived or not?)
They could have killed him.( did they kill him or not?)
you said we use could have to talk about something was possible at some time but didn't happen. How can we know if this happened or maybe happened?
thanks to the all team members

Khuder, I'm from Brazil and I'm not 100% sure about what I'll tell you now, but, in my opinion, you need to learn how to use only the modal "Could", as soon as you learn it, you will be able to use it with "have" cause it will sound clearer for you. In your example "They could have arrived", it might be more difficult if you analyse it out of a context for example. Oh, they could have arrived many hours ago, lets prepare something to them... So in this case they "maybe yes/not have arrived many hours ago, it's a possibility but you prefer to prepare something to them...
They could have killed him... Is not 100% of sure that they killed him, maybe yes maybe not, it will rely on an investigation...
I don't know if I helped you but I tried.
Thanks
Bye bye.

Hello khuder,

Modals have lots of different uses, so it's best to take them in small doses! 'could have' implies that the possibility existed but was not realised, so, for example, in your two examples, they did not arrive hours ago and they did not kill him. If you want to make it clear that something was possible and did happen, most of the time you'd probably just use a past simple form, e.g. 'they arrived hours ago', 'they killed him'.

All the best,
Kirk
The LearnEnglish Team

Hi there,
I'm always baffled by the 'would'. how to differentiate that would in the sentence is conditional or talking about the possibility ( like might or could )?. Do we need to consider the whole context to differentiate between these two? for instance, this paragraph is talking about the Computer Networking terminology.

" Data link layer protocols add a trailer to the end of each frame. The trailer is used to determine if the frame arrived without error. This process is called error detection and is accomplished by placing a logical or mathematical summary of the bits that comprise the frame in the trailer.

Error detection is added at the data link layer because the signals on the media could be subject to interference, distortion, or loss that would substantially change the bit values that those signals represent."

It would be great if you could help me on this regard.

Regards,
Kiran

Namaste Kiran,

'would' and all of the different modal verbs can indeed be difficult to learn to use, as they all have multiple uses is different contexts. 'would' is not used to talk about possibilities in the same way as 'may' and 'might'; rather, it communicates the idea of something unreal (e.g. because it's hypothetical or imaginary).

We don't normally comment on texts from other sources, but I'll try to help you with this one since it's very specific. In the fourth sentence, the 'because' clause is talking about a hypothetical situation, more specifically a situation in which the signal is subject to interference. Since this signal interference situation is hypothetical, the changes in the bit values that would result because of it are also hypothetical. The hypothetical nature of this signaled by 'would'. If we said 'will', it implies more reality than is appropriate for this situation.

Does that help?

All the best,
Kirk
The LearnEnglish Team
 

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