which, what and who: question words

  • Determiners
    We can use which and what before nouns to ask questions about people or things.
      Which teacher do you like best?
      Which colour do you want — green, red, yellow or brown?
      What writers do you like?
      What colour are your girl-friend’s eyes?

    We usually prefer which when we are choosing between a small number, and what when we are choosing between a large number. Before another determiner (for example the, my, these) or a pronoun, we use which of.

      Which of your teachers do you like best?
      Which of them do you want?
  • Pronouns
    We can use which, what and who as pronouns, without nouns. We use who, not which, for people.
      Who won — Smith or Fitzgibbon?
      Which would you prefer — wine or beer?
      What would you like to eat?
      We usually use who, not whom, as an object.
      Who do you like best — your father or your mother?
      (Whom do you like best . . . ? is very formal.)