Jim: Mum, May I go to the library?
Mother: Of course you could Jim, but you mustn’t stay very long.
Jim: May stay until 8 o’clock?
Mother: No, you can’t because the concert starts at 8.30.
(At the library)
Jim: Can I look at the latest “Musician” magazine, please?
Librarian: Yes, you can, but remember that you can’t take it out of the library.