can't/mustn't

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sevengem

Senior Member
Chinese
--May I take this book out of the reading room?
--No, you ___. You read it in here.

The answer is "mustn't". But I am wondering whether "can't" or "may not" is also right since the question begins with "can".
 
  • se16teddy

    Senior Member
    English - England
    This area is heavily loaded with personal preference, often presented as correct or standard grammar.

    Lots of people use "can't" in this sense of "do not have permission", and I suspect it is the option you are most likely to hear here. However, some people disapprove of this usage as sloppy, ungrammatical and so on; and it seems that the author of Sevengem's text book is in this camp.

    Lots of people would be happy with "may not" here. However, other people might think it oddly formal or authoritarian.

    "Mustn't" sounds odd to me here - it suggest to me "unethical", rather than "against the rules" or "permission withheld".
     
    Last edited:

    Einstein

    Senior Member
    UK, English
    I agree with EMP; "can't" and "may not" (preferable "can't") express the normal situation, meaning it is not permitted.

    "No, you mustn't" suggests a situation where the person is insisting on taking the book away and the other person is alarmed about the consequences.

    EDIT: I was concentrating on the difference between "can't" and "mustn't". On the difference between "may" and "can", I'd say that in this case "can" sounds more natural, because it's an established impossibility. I might say "you may not" if I were the person deciding, but I'd say "you can't" to mean that the rules don't allow it.
     

    velisarius

    Senior Member
    British English (Sussex)
    In my opinion the best answer to "May I..?" is "No, I'm afraid you can't.":D

    "No, you may not" sounds sharp, but "I'm afraid you can't/aren't allowed to" is just as polite as "May I..?"
     

    Englishmypassion

    Senior Member
    India - Hindi
    EDIT: I was concentrating on the difference between "can't" and "mustn't". On the difference between "may" and "can", I'd say that in this case "can" sounds more natural, because it's an established impossibility. I might say "you may not" if I were the person deciding, but I'd say "you can't" to mean that the rules don't allow it.
    That's how I take it -- "can/can't" expresses more clearly that something is allowed/not allowed according to the rules. "May" for giving or refusing personal permission.
     
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