Who, which and what. An ambitious aim for this modest column, to deal with these three pronouns. Basically, "who" refers to people, "which" and "what" to things. In
questions, "which" indicates a limited choice (Which color of the rainbow is at the top?), and "what" is good for an unrestricted range (What is your favorite color?).
As relative pronouns, "which" means "ktorý/á/é" for things (That's the pullover which I've been looking for.), and "who" means "ktorý/á/é/ého" for people (What's the
name of the actor who played Dirty Harry? She would not tell us who she had been out with.). "What" means "to, čo" as in: Don't listen to what any politicians say - wait and see what they do. "Čo?"
is "What?" in direct questions (What have you done?), but it is "which" as a relative pronoun (This is the chewing-gum which I like best. It has a fantastic taste which lasts and lasts.).