Interrogative Pronouns :
The interrogative pronouns (who/which/what) introduce questions.
What is that?
Who will help me?
Which do you prefer?
Which is generally used with more specific reference than what. If we're taking a quiz and I ask "Which questions give you the most trouble?", I am referring to specific questions on that quiz. If I ask "What questions give you most trouble"? I could be asking what kind of questions on that quiz (or what kind of question, generically, in general) gives you trouble. The interrogative pronouns also act as Determiners:
It doesn't matter which beer you buy.
He doesn't know whose car he hit.
In this determiner role, they are sometimes called interrogative adjectives.
Like the relative pronouns, the interrogative pronouns introduce noun clauses, and like the relative pronouns, the interrogative pronouns play a subject role in the clauses they introduce:
We know who is guilty of this crime.
I already told the detective what I know about it.
Related Links :
From Interrogative Pronouns to HOME PAGE