What asks about any option, which asks you to choose from a known set. What book are you reading? The range of books is open. Which book do you want, this one or that one? The options are in front of you or have already been named.
what or which — can you pick the right one?
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what + noun? (any option); which + noun? (from a known set); which of + the/these/you; which one?
- What music do you usually listen to when you're working?
- Which bus goes to the airport, the 12 or the 15?
- Which of your colleagues speaks Spanish?
What changed
First versionWhat of these two laptops is cheaper?
RevisionWhich of these two laptops is cheaper?
Which of these is a common pattern, and it's tempting to build what of the same way. But only which can come before of: which of these, which of you. What doesn't combine with of in this kind of question.
With time, size and kind, people usually say what in conversation, even when there are only a few options: What size are you? What time does the museum close? Which appears when the options are literally in front of you: Which size do you want, the M or the L?
Your turn
There are two rooms left. ___ one would you like, the one with a balcony or the quiet one?
Show the answer
Which — There are two options, and both are named: the one with a balcony and the quiet one. Choosing from a known set means which. Nobody says what one.
Write a question to a colleague about where to go for lunch. Suggest exactly two specific places and name both.
Which café should we go to for lunch, the Italian place or the new sushi bar?
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