RELATIVE PRONOUNS AND ADVERBS

relative pronoun	use	example
who	subject or object pronoun for people	I told you about the woman who lives next door.
which	subject or object pronoun for animals and things	Do you see the cat which is lying on the roof?
which	referring to a whole sentence	He couldn’t read which surprised me.
whose	possession for people animals and things	Do you know the boy whose mother is a nurse?
whom	object pronoun for people, especially in non-defining relative clauses (in defining relative clauses we colloquially prefer who)	I was invited by the professor whom I met at the conference.
that	subject or object pronoun for people, animals and things in defining relative clauses (who or which are also possible)	I don’t like the table that stands in their kitchen.

relative adverb	meaning	use	example
when	in/on which	refers to a time expression	the day when we met him
where	in/at which	refers to a place	the place where we met him
why	for which	refers to a reason	the reason why we met him