Examples: WHO is looking at Mary? (Peter is looking at her.) WHO is Mary looking at? (She's looking at Peter.)
WHAT - Things, unlimited choice.
Examples: WHAT do you want? WHAT are you taking out of your pocket? WHAT do you smoke? WHAT is in your pocket?
WHICH - Things or people, limited choice.
Examples: Things: WHICH pocket is your pen in? (I have 2, 3 or 4 pockets) WHICH pen is in your pocket? (I have 2 or 3 pens) WHICH pipe are you smoking? (I have two.) People: Which manager has a BMW? Which receptionist is on the phone?
_____ is president of Italy?
Who
What
Which
_____ is your favorite actor?
Who
What
Which
_____ is Mary's job?
Who
What
Which
_____ do you like best, Italian food or Chinese food?
Who
What
Which
_____ lives in Buckingham Palace?
Who
What
Which
_____ costs more, a Rolls Royce or a Jaguar?
Who
What
Which
_____ programme do you want to watch this evening, the film or the reality show?