Suggestions and obligations

Level: beginner


We use should and shouldn't to make suggestions and give advice:

You should send an email.
You shouldn’t go by train.

We also use could to make positive suggestions:

We could meet at the weekend.
You could eat out tonight.

Level: intermediate

We can use conditionals to give advice:

Dan will help you if you ask him.

Past tenses are more polite:

Dan would help you if you asked him.

Suggestions 1


Suggestions 2


Level: beginner


We use must or need to to say that it is necessary to do something:

You must stop at a red light.
Everyone needs to bring something to eat.
You can wear what you like, but you must look neat and tidy.

We use mustn't for prohibitions – to say that it is necessary to not do something:

You mustn't make any noise in the library.
You mustn't say anything to her. It's a surprise.

We use had to (positive) and couldn't (negative) if we are talking about the past:

Everyone had to bring something to eat.
You couldn't make any noise in the library.

Obligations 1


Obligations 2



Average: 3.9 (24 votes)

Submitted by tutoring on Fri, 22/03/2024 - 06:01



‘You _____ stop at red light.’ 

In this sentence, can we put both ‘must’ and ‘have to’? 

Yes, it is really simple, and wouldn’t generally require much thought, but here is the problem: 

I was looking at some online exercises the other day, and in that sentence, the source suggested ‘have to’ as the correct answer, which confused me.

I didn’t agree because, as we know, ‘must’ is for internal obligations, and also, for rules coming from authorities. 

On the other hand, ‘have to’ expresses external obligations. 

So, if no additional context is provided, we can be dealing with different situations:

  • One person could be telling this sentence to another to remind them the rule, external obligation, thus ‘have to’
  • One person might be telling the other what they internally believe is right, thus ‘must’
  • Someone could be just stating it as a general rule set by authorities, thus ‘must’.

So, why is ‘have to’ the (only) correct answer given?

I think, both ‘must/have to’ should be given as acceptable answers (as there is no context), or if there is only one answer, it’s obviously ‘must’ and not ‘have to’.

I might be making a fuss over nothing, as there are too many careless mistakes online, but would love to hear your thoughts on this, just to be sure.

Thank you in advance. I appreciate your help a lot.

Hi tutoring,

Yes, I agree with you that both "must" and "have to" are fine in this sentence. As you correctly point out, knowing the full context or the exact intended meaning may lead us to prefer one form or the other, but we don't have that information.

I would also add that in real life usage, there is a lot of overlap between "must" and "have to". The internal/external distinction is somewhat useful, but I don't think every example can neatly fall into one of the two categories. In my view it's better to consider these as general patterns of usage, rather than hard rules.

I hope that helps.


LearnEnglish team

Submitted by Kumaraswamy on Sat, 25/03/2023 - 08:10


Can we mix up modal verbs as in the following sentences?

I can guarantee you that your son will score more this time.

I can guarantee you that your son would score more this time.

I could guarantee you that your son will score more this time.

I could guarantee you that your son would score more this time.

If so, what does each of them mean?

This might once again be a repeated question and yet a question of this kind still bothers me. So, I request that you answer this question.

Hello Kumaraswamy,

Whether or not these make sense depends on the situation they're used in. Please explain how you think these sentences could be used in a situation, and then we can help you with any misunderstandings.

We're happy to help, but it's asking quite a lot of us to think of the different situations and then explain them all.

All the best,
LearnEnglish team

1. I can guarantee you that your son will score more this time.

2. I can guarantee you that your son would score more this time.

3. I could guarantee you that your son will score more this time.

4. I could guarantee you that your son would score more this time.

As far the first sentence, it's got can and will and so it can come across what they both mean.

Whereas, the other sentences have got the modal verbs used in the present and the past forms.

My question is,
Can we use two different modal verbs in two different tense forms as the modal verbs used in the above sentences? If so, pls explain what do the modal verbs in the last three sentences above mean in terms of the uses on which they have been used in those sentences?

Or is there any rule that the tense forms of two different modal verbs be not changed in order for them to stick to the same tense form even when they both are used in the same sentence?

I m afraid, I might not have made my question clear to you and yet I sort of believe that I have tried my best to get it over to you.

I request that you help me with the answer to my question.

Hi Kumaraswamy,

There isn't any rule that says that present/past modals cannot be mixed. The important thing is what the modals actually mean, to see if the sentence makes sense overall. Although we can describe "could" and "would" as past tense forms, that is not the main issue in these examples, because "could" and "would" do not actually refer to the past here. "Could" in 3 and 4 refers to a possibility in the present (i.e., making the guarantee now, at the moment of speaking). "Would" in 2 and 4 refers to a present or future event (i.e. scoring more this time).

The sentences with "would" show an action that is conditional, i.e. it is dependent on something else. For example: I can guarantee you that your son would score more this time, if he weren't injured. Sentences 2 and 4 do not show what "scoring more this time" is dependent on, so the idea seems incomplete.

In comparison with sentences 1 and 2 using "can", sentences 3 and 4 using "could" also show that the "guaranteeing" action is dependent on something, e.g. I could guarantee you that your son would score more this time, if he weren't injured

Sentence 3 is unusual because the action using "will" is expressed with more certainty than the guarantee, which uses "could" and seems conditional. But if the speaker is confident that the action "score more" will happen, I would expect that the guarantee would be expressed with at least the same level of confidence. Sentence 1 seems better than sentence 3, for that reason.

I hope that helps to understand it.


LearnEnglish team

Submitted by Kumaraswamy on Tue, 21/03/2023 - 15:37


Hello teachers,
What do 'for' and 'to' mean when used after adjectivesm

It's important for me to go to the party.
It's important to me to go to the party.

The new signs will be confusing for the tourists.
The new signs will be confusing to the tourists.

The above sentences are for just an example. What I do want to know is the distinction between for and to when used after adjectives.

Hello Kumaraswamy,

There is no single answer to this, I'm afraid. Collocating prepositions have a range of meanings rather than a single meaning.


With regard to your specific examples, I would say this:

important to me > my personal sense of what is important; this is about my values or preferences.

important for me > this suggests something more external; it is important because of my career, for example.


I don't see any real difference between confusing for and confusing to here.


You may find these pages useful on this topic:



The LearnEnglish Team

Submitted by Kumaraswamy on Sat, 18/03/2023 - 12:57


Could you explain "as of now" & "as from now"?

Is 'as of now' an alternative to 'untill now' while 'as from now' an alternative to 'from now on'?

What do they exactly mean?

Thank you for the clear answer to my last question.

Hi Kumaraswamy,

Both phrases mean "from now on". However, "as of now" is more commonly used than "as from now".


LearnEnglish team

Submitted by Kumaraswamy on Fri, 17/03/2023 - 14:08


We have lost the keys.
What do we do? Vs What should we do?

A teacher to one of his students,
Why don't you come to the front and write the answer on the blackboard?
Why won't you come to the front and write the answer on the blackboard?
Which one of the two would fit the context and why? Why not the other one?

Father: Son, you are already late for work. What's the matter with your car.
Son: My car won't start.
My car doesn't start.
My car is not starting.
Which one of the three is correct and why?
What if we used the other two and what would they mean?

Hi Kumaraswamy,

Taking them literally, What do we do? asks what the next step is, in a factual way, suggesting that there is a planned procedure for this situation. What should we do? asks what action is most appropriate. This difference seems not so important in this situation, as both questions lead to the same answer (e.g. we should search for the lost keys).

Both of the teacher's questions fit the context, but they mean different things. Why don't you ... ? is a suggestion. The teacher is inviting the student to write the answer. Why won't you ... ? is not a suggestion but a question about the student's unwillingness. It means that the student is unwilling to write the answer, and the teacher wants to know the reason why.

My car doesn't start describes a general situation. It means that the car generally has problems, not just in this particular moment. In comparison, My car isn't starting refers to this particular moment. If the car was working fine recently but only now has suddenly stopped working, it would be better to say this. My car won't start includes "won't", which indicates a person's unwillingness to do something (e.g. I asked him to come with me but he won't do it). This unwillingness typically describes a person, as in my example, but may also describe the behaviour of a machine or other object that does not behave in the way that we want (even though a car obviously does not have a 'will' of its own). Another example is: The door is blocked. It won't open.

Does that make sense?


LearnEnglish team

Submitted by Kumaraswamy on Fri, 17/03/2023 - 05:47


to continue to do something despite difficulties or opposition, in a way that can seem unreasonable

This is one of the uses of the verb 'persist' according to

In that, what does 'can' actually mean?
What if we replaced 'can' with 'could' or 'might' or 'would'
Would we get a different meaning then?

Thank u.

Hello Kumaraswamy,

Can, could, might and would are all possible here but there are some differences in meaning.

Can tells us that it is possible that the word will seem unreasonable. It suggests that using the word is taking a chance or a risk.

Could and might tell us how the word might be interpreted - there is a chance people will understand it like this. To my ear the focus is more clearly on the listener's interpretation here.

Would tells us with certainty how people will understand the word. There is no doubt involved; it is a certain result rather than a possibility.



The LearnEnglish Team

Submitted by Kumaraswamy on Wed, 15/03/2023 - 03:57


Hello teachers,
Wear a mask_______you will be safe.(and or so)
Which one of the is correct and why?
What if the other one was used?

I got him to do the task for me.
I got him doing the task for me.
What's the difference between them in terms of to+do and doing respectively?

Thank you.

Hello Kumaraswamy,

Both 'and' and 'so' are correct here, though there's a slight difference in meaning. 'so' communicates a stronger sense of purpose, i.e. the idea that wearing a mask will make you safe. 'and' implies this, but doesn't make the causal connection explicit.

As for the other pair of sentences, there is a difference of emphasis. The first one is general and communicates the task was done and that you got the person to do it for you.

The second also communicates that you got someone to do the task for you, but focuses more on getting the task started (the continuous aspect 'doing') or at least in process (perhaps he had begun it in the past and then stopped and then you got him started again). It's not clear whether the task was finished or not. It could be that it was finished or it could be that it was ongoing. The sentence isn't specific enough in itself to communicate this idea. To do that, you'd need to add another phrase (e.g. 'I expect him to finish it today' or 'It took him three hours to finish it').

All the best,
LearnEnglish team

This is what is given as one of the uses of the verb 'get' on

[transitive] to make, persuade, etc. somebody/something to do something

get somebody/something to do something

Eg. I couldn't get the car to start this

He got his sister to help him with
his homework.

You'll never get him to understand.

get somebody/something doing something

Eg. It's not hard to get him talking—
the problem is stopping him!

Can you really get that old car
going again?

What still gets me is the difference between 'get+object+to+verb and get+object+verb+ing

I will get him to understand the problem.
I will get him understanding the problem.

I m absolutely sorry that i have again repeated the same question. Without having any resentment for me, clear my doubt pls.

Thank u.

Hello Kumaraswamy,

What the two forms share is the idea of making somebody/something do something. It could be by persuasion or it could be by brute force, but the idea is that it takes some work to make it happen.

The difference is that the '-ing' form refers to the start of a process or activity, whereas the infinitive form is more general. It might help to imagine an old car. It can be difficult to start an old car or machine.

I don't think 'I will get him understanding the problem' is a good example because the idea of understanding isn't something that has a clear beginning like starting a car does. I'm not sure if that's a sentence you made up or one you found somewhere, but in either case I don't think it's going to help you understand this.

Hope this helps.

All the best,
LearnEnglish team

I couldn't thank u more, teacher.

Could you differentiate between,
I prefer to drink tea rather than coffe.
I would prefer to drink tea rather than coffee.
I rather want to go in my car.
I would rather go in my car than in my friend's car.

Thank u, teacher.

Hi Kumaraswamy,

"I prefer" is a more general statement about what you generally prefer in your life. "I would prefer" is talking about what you want at a particular time, day or occasion. For example, you could say this if you and your friends are discussing whether to have tea or coffee that afternoon. It's a statement about what you want in that particular moment (not in general).

The two sentences with "rather" have different meanings of "rather". In the first one, "rather" means "to some degree" or "somewhat". In the second one, it is part of the phrase "rather than", which means "instead of". The first sentence does not have this comparative meaning.

I hope that helps! If you have more questions about "would", we welcome you to post them on our page for "will" and "would" (linked).

Best wishes,


LearnEnglish team

Submitted by Girijakumar on Sat, 11/03/2023 - 03:44


Hello teacher,
Could you tell me the exact difference between, "You could say..." and "You might say..."?

What's the degree of possibility between,
Your keys may be/could be/might be in your car.
Which one gives us the most possibility and more possibility and less possibility?

Thank you.

Hello Girijakumar,

Remember that each modal verb can have a range of meanings. For example, could can be used for ability, possibility, probability, permission etc. In addition, each modal meaning can be expressed by multiple verbs. For example, probability can be expressed by might, could, may, can't, must etc.

This means that it's not really possible to answer your first question without a clearer context, I'm afraid. We'll be happy to comment if you can provide that context, of course.


The context is clearer in your second question. These three forms are essentially interchangeable and I don't think any of these shows a greater or lesser degree of probability. The way in which each is articulated (tone, stress and even facial expression), or the wider written context in which they appear (the text before and after each) will determine the degree of probability expressed.



The LearnEnglish Team

Thankful for your reply, sir.

Sorry that i didn't provide a clearer context whereby it wasn't possible for u to answer my first question.

You can use 'can' to make requests in a friendly way.
You could use 'can' to make requests in a friendly way.
You might use 'can' to make requests in a friendly way.

Can, could and might are used to make suggestions. They must have some subtle difference between them. That doesn't matter to a native speaker as they know that. So isn't in the case of the rest who learn it as a second language.I really would like to know what that subtle difference is so as to be able to satisfy my students.

My second question was,
"What's the difference between
Your keys may be in the car.
Your keys could be in the car.
Your keys might be in the car.
Your keys would be in the car.
in terms of the degree of possibility of the keys being in the car?

And your answer to that was,
The context is clearer in your second question. These three forms are essentially interchangeable and I don't think any of these shows a greater or lesser degree of probability. The way in which each is articulated (tone, stress and even facial expression), or the wider written context in which they appear (the text before and after each) will determine the degree of probability expressed.

However, they must have got some subtle difference between them. I request that you describe that subtlety to help not to end up in embarrassing situations while teaching them to my students.

Sometimes, when we want to express our criticism or resentment for why someone didn't do what we had expected them to, we prefer to use either 'could' or 'might' as,

I didn't know I had to submit the assignment in two days. You could/might have told me earlier that but u didn't, why?

What's the difference between could and might in the sentence?

When making negative deductions about a past action, we use either can't or couldn't as,

She was not in the office at the time of the theft so she can't/couldn't have done committed that.

What's the difference between can't and couldn't in the sentence though they both refer to a past action?

Sir, I know that model Verbs are kind of tricky as almost many of them have similar uses. But still, they also have subtle differences that differentiate them from each other as to why native speakers use them accordingly. It is essential for those who learn English as a second to know all of the subtle differences.
So, i plead you to help me with the hidden subtle differences between the model verbs in all those sentences.

Thank you, sir.

Hello again Kumaraswamy,

I don't agree that different forms must have some subtle differences between them. Sometimes they are simply alternatives which the speaker can choose freely between.

In terms of probability I don't think may, might and could have any inherent difference. They express a possibility; the likelihood of this possibility is expressed by how they are said and in what context rather than being an inherent part of the meaning of each modal verb.

Would is a little different. It expresses expectation on the basis of some other information rather than simply a possibility. There is often an implied condition involved: Your keys would be in the car if you had put them in the normal place.

In another answer to you I discussed the difference between might and could in terms of suggestions.


Could have and might have are also interchangeable in the context of expressing criticism. I understand your frustration here: it would be satisfying for both teachers and learners to be able to give a clear distinction and place the items in a nice clean hierarchy or sequence. Unfortunately, that is not possible and I think it would be a disservice to your students to suggest that there is a clear difference between the two.


With can't have and couldn't have both forms are possible to express deductions about the past. Can't have puts the focus on the current state (she is innocent) while couldn't have puts the focus on the action (she didn't do it), I would say, so it's something of a choice for the speaker in terms of emphasis.


I hope those answers help. Please note that generally we prefer not to answer questions on multiple areas with numerous examples. Partly this is a time issue - we are a small team and it takes a long time to write an answer such as this, but it's also because a long answer is less helpful to other learners who may not have the time to search through for the particular piece of information they are looking for. Please try to keep questions short and on a single topic/example.



The LearnEnglish Team

I don't know how to express my thanks to u as u showed a lot of patience for my question and answered it. I m sorry that i asked u multiple questions on the same and already repeatedly dealt with model verbs bcos of my over-curiosity about them. I will also make sure that I always keep to what u have asked me to in future. By the way, to me ur team must be the best team ever that's purely intended to be at the service of all English aspirants across the world.
Thank u.

Submitted by howtosay_ on Thu, 22/12/2022 - 01:35



As far as I know, we are to use "Should" in questions, but what if situation refers to "must" or "have to"? Could I ask "Must you be silent?" or "Do I have to be silent?" or "Have I got to be silent?", for example. And if the question is "Should we send an email", might the answer be "We must" or "We have to".

And one more question. I'm sorry, but I'm very curious about the sentence "We use mustn't for prohibitions – to say that it is necessary TO NOT DO something". Do you say "It is necessary NOT TO DO something" or is it a mistake?

I'm so much grateful for your work, and thank you very much for your answer beforehand!!!

Hello howtosay_,

There's no reason why you can't use modal verbs in questions - should is not special in this regard. Generally, 'have to' is preferred in questions as 'must' sounds much more formal and even old-fashioned, but grammatically both are fine.


Both 'necessary to not do' and 'necessary not to do' are fine. I think the former is more common, but this may be a question of dialect.



The LearnEnglish Team

Profile picture for user Ahmed Imam

Submitted by Ahmed Imam on Tue, 22/11/2022 - 09:10


Hello. Could you please help me? Which one is correct?

- A: What is the rule about visiting people in hospital?

B: You (must - have to) go between 2 and 5 o'clock in the afternoon.

Thank you.

Hello Ahmed Imam,

It'd be more natural for B to say 'Visiting hours are between ...' or 'You can only go between ...' here. If you're testing the difference between 'must' and 'have to', I'd recommend writing a different sentence.

All the best,
The LearnEnglish Team

What about the following sentence: - I (must - have to) be at home before 10 pm. That's a family rule.
Thank you.

Hello Ahmed Imam,

I'd say 'have to' is better here since it sounds like an external obligation. In general, we prefer 'have to' to talk about obligations imposed by external rules. 'must' can be used to give strong orders to others and it is often used to talk about what one feels one needs to do, though, so it's also possible.

Hope this helps.

All the best,
The LearnEnglish Team

Submitted by g-ssan on Fri, 14/10/2022 - 20:44


Sir ,
Does should use in obligation ? i imagine it has same meaning with must and ought to . Am I right ? .

Hello g-ssan,

Generally, should and ought to express advice rather than obligation. These verbs imply that there is a choice, whereas must suggests that there is no choice. Of course, such meanings are very much dependent on the context in which the words are used.



The LearnEnglish Team

Submitted by g-ssan on Fri, 14/10/2022 - 19:42


Hello sir ,
Are need to and had to modal verb ?
Why they took (s) third person in example above "every one needs to bring something to eat "?
Correct me if I am wrong please ?

Hello g-ssan,

These are examples of what are sometimes called semi-modal verbs, which means verbs which have some features of modal verbs but not all. In some cases they are verbs which are in the process of changing their form over time. For example, questions and negatives with 'need' are generally formed with 'do':

Does he need to come in person?

You don't need to finish it today.

However, you can use full modal forms:

Need he come in person?

You needn't finish it today.

These forms are becoming less common and will eventually, probably, disappear from the language. It's an example of the language evolving before our eyes.

You can read more about need as an example here:



The LearnEnglish Team

Submitted by Faii on Mon, 25/07/2022 - 08:41


"It was going to be a long day.I was supposed to clean up all the stables,and then start on the garden"

Is it clear from here that I have done the things I was suppose to do ?

Hello Faii,

No, it's not. This sentence does not tell us whether or not the speaker did or will do those things. It tells us how the day looked at the start, not what happened after that. Perhaps the speaker did all of those jobs, or perhaps they decided to leave everything and take the day off instead. This sentence does not tell us.



The LearnEnglish Team

Submitted by Mayura on Sun, 26/06/2022 - 16:48


Hello, Sir.
I wanted to know if "should have to" still expresses "advice". Are the 3 sentences the same in meaning, especially 2 and 3.
1. You should do exercise every day to be fit.
2. You should have to do exercise every day to be fit.
3. You had better do exercise every day to be fit.
Best Wishes!

Hello Mayura,

'Should have' expresses advice in the sense of identifying a better alternative in the past which was not taken. For example, I go to the restaurant and order a pizza, but the pizza is not good so I think 'I should have ordered lasagne!'

The form is should have + verb3 / past participle (should have ordered).


Your examples do not contain 'should have' in this form.

The first sentence describes advice about the present (specifically, general time): should + base form (should do)

The second sentences also uses should for present time. The verb here is 'have to', which is not a past participle: should + have to + verb (should have to do). It has the same meaning as the first sentence with the addition on obligation.

The third sentence gives advice about the future. It does not describe advice in general but rather what the listener should do in the future. Thus, it gives advice but has a different meaning to the first sentence. The form here is had better + verb (had better do).



The LearnEnglish Team

Submitted by HieuNT on Tue, 18/01/2022 - 19:42


Hello, British Council Team,

In famous grammar books or online dictionaries, I didn't see any reference to the use of of "should not" after "suggest".

However, I've seen this structure widely used in this way.

E.g.: "What we won't see, however, is politicians suggesting that we shouldn't have a National Health Service."


My question is: Is this phenomenon considered "Standard English", or it's just the same case as double/multiple negatives which is acceptable in informal contexts only because they are commonly used but are inappropriate in more formal contexts?

Should I use "should not" this way or should I stick to the subjunctive (not + infinitives) when it come to negative suggesting sentences?

Thank you, and I hope to hear from you soon.
Hieu Nguyen

Hello Hieu Nguyen,

You're correct that we don't use suggest + should (not). Suggest can be followed by a that-clause which includes 'should', however, and this is what your sentence is an example of:
> She suggested that we shouldn't have a National Health Service.

Other modal verbs can be used:
> She suggested that we couldn't have a National Health Service unless we raised taxes.
> She suggested that we mightn't have a National Health Service in the future.

A verb-ing form is also possible and is used when making a proposal:
> She suggested not having a National Health Service. Instead, ...

And, as you say, the subjunctive form is also an option, though it tends to be used in more formal contexts:
> She suggested that we not have a National Health Service.

The LearnEnglish Team

Hello Mr. Peter,

Thank you for your explanation.
However, I believe the way I put my ideas was not clear.

I know that "suggest" cannot be followed directly by "should (not)", as in:
>She suggested shouldn't have a National Health Service.

What I was asking is, is it standard English to use "should (not)" in "suggest + that clause" or is it a habitual use (like double negatives) which then become acceptable in informal contexts, as in:
> She suggested that we shouldn't have a National Health Service.

Hieu Nguyen

Hello again Hieu Nguyen,

It's fine to use 'should not' like this. Your example is perfectly correct and in no way non-standard.

The LearnEnglish Team

Thank you for your clarification, Mr. Pete.

Normally, I would only use "should not" after "suggest" to mean "show" or "express", as in:
> The result suggests that we shouldn't...

Now, I think I'll start using "should not" after "suggest" when I make a recommendation or give someone else advice in some case without worrying too much.