Question

What are the most common relative pronouns

Answer 1

 The most common relative pronouns are :

who- which- that- whom- whose 

We use who to represent defining and non-defining relative clauses

ex:

A doctor is a person who works in hospital. 

Whom is used to refer to people when the person is the object of the verb 

He is the person whom I admired most. 

Whose is used to express possession by people and animals.

ex:

The man whose car is red, is my teacher.

Which refers to objects and animals. It's used to express defining and non-defining relative clauses

ex:

This is the house which I bought yesterday. 

That is used to refer to animals or things and persons. We can use it to replace who- which - whom 

The 7.15 is the flight  that you need to get