Look at these examples to see how can, can't, must, mustn't, have to and don’t have to are used.
You can put your shoes and coat over there.
You can't leave your bike there.
I must call the electrician and get that light fixed.
You mustn't worry about me. I'll be fine.
You have to have a licence to drive a car.
You don't have to have a licence to cycle on the roads.
Try this exercise to test your grammar.
- Grammar test 1
Read the explanation to learn more.
We often use verbs with modal meanings to talk about permission and obligation.
We often use can to ask for and give permission.
Can I sit here?
You can use my car if you like.
Can I make a suggestion?
We also use could to ask for permission (but not to give it). Could is more formal and polite than can.
Could I ask you something?
Could I interrupt?
Could I borrow your pen for a moment, please?
May is the most formal way to ask for and give permission.
May I see your passport, please?
Customers may request a refund within a period of 30 days.
These pages may be photocopied for classroom use.
We use can't and mustn't to show that something is prohibited – it is not allowed.
We use can't to talk about something that is against the rules, particularly when we didn't make the rules.
What does this sign say? Oh, we can't park here.
You can't take photos in the museum. They're really strict about it.
Sorry, we can't sell knives to under-18s.
We use must not to talk about what is not permitted. It is common on public signs and notices informing people of rules and laws.
Visitors must not park in the staff car park.
Baggage must not be left unattended.
Guests must not make noise after 10 p.m.
We use mustn't particularly when the prohibition comes from the speaker.
(Parent to child) You mustn't say things like that to your sister.
(Teacher to student) You mustn't be late to class.
I mustn't let that happen again.
We use have to and must to express obligation. There is a slight difference between the way we use them.
Have to shows us that the obligation comes from outside the speaker.
We have to wear a uniform when we're working in reception.
(Student to teacher) When do we have to hand in our homework?
Al has to work tomorrow so he can't come.
We sometimes call this 'external obligation'.
Must expresses a strong obligation or necessity. It often shows us that the obligation comes from the speaker (or the authority that wrote the sentence).
I must phone my dad. It's his birthday today.
(Teacher to student) You must hand in your homework on Tuesday or you will lose ten per cent of your mark.
(Sign on a plane) Seat belts must be worn by all passengers.
Note that we don't use must to express obligation in the past. We use have to instead.
I had to pay £85 to renew my passport last week.
don't have to
We use don’t have to to show that there is no obligation. You can do something if you want to but it's not compulsory.
You don't have to wear a tie in our office but some people like to dress more formally.
You don't have to go to the bank to do a transfer. You can do it online.
You don't have to come with me, honestly. I'll be fine!
Do this exercise to test your grammar again.
- Grammar test 2
Hi, I have a question about a sentence.
Sentence: There are French lessons at my high school but I don´t have to take them.
Can I use this sentence to express that something(the French lessons) is available but is not compulsary to do it?
Yes, exactly! That sentence means the French lessons are optional. There is no obligation to take them.
I have a problem with a following clause: Could you help me move these boxes?
I need to know for my upcoming English test that if this clause is interpreted as epistemic, deontic or dynamic.
I know that if someone is asking for permission then it would be interpreted as deontic, and if we are talking about someone's willingness to help then it would be dynamic as in "I have asked him to help us but he won't."
So how can I know if this clause is deontic or dynamic because somebody is asking not permission, but someone's willingness to help?
Thank you already for your help!
This is not a question for this site, I'm afraid. This site is for language learners; you need a site for people studying linguistics for this kind of question.
I recommend the appropriate section of StackExchange:
Good luck with your test!
The LearnEnglish Team
Please, could you explain which of the two grammatical structures is correct?
Wouldn't it be better to turn the written text into graphics?
Would it not be better to turn the written text into graphics?
Thanks a lot
Actually, they are both correct!
Jonathan, thanks a lot
I came across with the word CAN NOT separated. Is it correct? I would like to know if the negative form of CAN is only CANNOT or we can use CAN NOT, and if so when we can use CAN NOT form? Thanks.
Thanks for your question! It should be a single word, cannot. Although people do sometimes write can not, it is an error. There is one exception - if "not" describes another verb, instead of "can", e.g. I don't mind if you don't want to go to the park. We can not go." (meaning = "we do not need to go" or "it's fine if we do not go"; "not" describes "go", not "can").
I hope that helps.
Hi LearnEnglish team,
I would like ask about the use of "have to" in the past perfect tense. Would you please supply some examples?