Can, could, may - permission
1-) You use ‘can’ or ‘be allowed to’ to talk about whether someone has permission to do something or not.
2-) You usually use ‘can’ to give someone permission to do something.
3-) You usually use ‘can’ or ‘could’ to ask for permission to do something.
1-) You use ‘can’ to say that someone is allowed to do something. You use ‘cannot’ or ‘can’t’ to say that they are not allowed to do it.
* Students can take a year away from university.
* Children cannot bathe except in the presence of two life savers.
You use ‘could’ to say that someone was allowed to do something in the past. You use ‘could not’ or ‘couldn’t’ to say that they were not allowed to do it.
* We could go to any part of the island we wanted.
* Both students and staff could use the swimming pool.
* We couldn’t go into the library after 5 pm.
2-) You also use ‘be allowed to’ when you are talking about permission, but not when you are asking for it or giving it.
* When Mr Wilt asks for a solicitor he will be allowed to see one.
* It was only after several months that I was allowed to visit her.
* You’re not allowed to use calculators in exams.
3-) In more formal situations, ‘may’ is used to say that someone is allowed to do something, and ‘may not’ is used to say that they are not allowed to do it.
* They may do exactly as they like.
* The retailer may not sell that book below the publisher’s price.
4-) When you want to give someone permission to do something, you use ‘can’.
* You can borrow that pen if you want to.
* You can go off duty now.
* She can go with you.
‘May’ is also used to give permission, but this is more formal.
* You may speak.
* You may leave as soon as you have finished.
5-) When you want to refuse someone permission to do something, you use ‘cannot’, ‘can’t’, ‘will not’, ‘won’t’, ‘shall not’, or ‘shan’t’.
‘* Can I have some sweets?’ - ‘No, you can’t!’ ‘I’ll just go upstairs.’ - ‘You will not!’
* You shan’t leave without my permission.
6-) When you are asking for permission to do something, you use ‘can’ or ‘could’.
If you ask in a very simple and direct way, you use ‘can’.
* Can / ask a question?
* Can we have something to wipe our hands on please?
‘Could’ is more polite than ‘can’.
* Could / just interrupt a minute?
* Could we put this fire on?
‘May’ is also used to ask permission, but this is more formal.
* May / have a cigarette?
‘Might’ is rather old-fashioned and is not often used in modern English in this way.
* Might I inquire if you are the owner?
7-) You have to use ‘be allowed to’ instead of a modal if you are using another modal, or if you want to use an ‘-ing’ form, a past participle, or a ‘to’-infinitive.
* Teachers will be allowed to decide for themselves
* I am strongly in favour of people being allowed to put on plays.
* They have not been allowed to come.
* We were going to be allowed to travel on the trains.