Who is the person sitting next to you?
Who are the people in the photograph?
Do you know who called me last night?
Who is the singer performing tonight?
I don't know who left their bag in the hallway.

Which book do you want to read next?
Which restaurant should we go to for dinner?
Do you know which movie won best picture at the Oscars?
Which route is the fastest way to get to the airport?
I can't decide which dress to wear to the party.