which, what and who: question words

which and what: the difference

Which and what are often both possible, with little difference of meaning.

• Which/What is the hottest city in the world?
• Which/What train did you come on?
• Which/What people have influenced you most in your life?

We prefer which when we have a limited number of choices in mind.

• We’ve got white or brown bread. Which will you have? (More natural than … What will you have?)
• Which size do you want – small, medium or large?

When we are not thinking of a limited number of choices, what is preferred.

• What language do they speak in Greenland? (More natural than Which language …)
• ***What’*s your phone number? (not Which is your phone number?)

Determiners: which and what

Before nouns, which and what can be used to ask questions about both things and people.

• 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 baby’s eyes?

which of

Before another determiner (e.g. the, my, these) or a pronoun, we use which of. Who and what are not normally used with of like this in modern English.

• Which of your teachers do you like best? (not Who/What of your teachers …)
• Which of us is going to do the cooking? (not Who of us …?)
• Which of these coats is yours? (not What of these …?)

Without nouns: who for people

When these words are not followed by nouns or pronouns, we generally use who, not which, for people.

• Who won – Smith or Fitzgibbon? (not Which won …?)
• Who are you going out with – Lesley or Maria?

However, which can be used in questions about people’s identity, and what can be used to ask about people’s jobs and functions.

• ‘Which is your husband?’ ‘The one in jeans.’
• *So Jessica’s the Managing Director. **What’*s Daniel?

note

For relative who and which (e.g. the man who … ), (see here).

For relative what (e.g. what I need is …), (see here).

For singular and plural verbs after who and what, (see here).