Interrogative Pronouns
From TEFL World Wiki
Interrogative pronouns are found in questions and this is why they are called interrogative (interrogate = ask).
The basic interrogative pronouns are:
Who made it to the top?
Whom did they hire for that job?
Which would you rather watch?
What was his reaction when he saw them?
Whose trainers are these?
The compounds forms whoever,whomever,whichever, and whatever are also interrogative pronouns.
who, whom and, sometimes, which are used to refer to people.
which and what are used to refer to things and animals.
who is used when it acts as the subject of a verb, while whom is used when it acts as the object.
which and what can also be used as interrogative adjectives.
who, whom and which can also be used as relative pronouns.
