Relative Part 1 - Who, Whom, Which, That

I. Who:

Who is used to replace people and function as a Subject:

Example: The man stole my wallet yesterday. He is wearing a blue coat.

The man who is wearing a blue coat stole my wallet yesterday.

II. Whom:

Whom is used to replace people and function as an Object:

Example: I interviewed some of the witnesses. They do not remember anything about the crime.

The witnesses whom I interviewed do not remember anything about the crime.

In standard written English, when the verb goes with a preposition, the preposition goes before whom.

Example: They discussed with the staff. He seemed to be nervous.

The staff with whom they discussed seemed to be nervous.

III. Which:

Which is used to replace things and function as a Subject or an Object:

Example: The newspaper is on the table. Please give me it.

Please give me the newspaper which is on the table.

You took the newspaper earlier. Please give me it.

Please give me the newspaper which you took earlier.

IV. That:

That is used to replace anything and function as a Subject or an Object:

Example: I saw a man and a dog in the park. They were playing Frisbee together.

I saw a man and a dog that were playing Frisbee together in the park.

V. Notes:

In modern English, we can use who instead of whom if there is no preposition before it:

Example: I met the family yesterday. They are very nice people.

The family who I met yesterday are very nice people. - CORRECT

I told the whole story with a police officer. He didn’t seem to care.

The police officer who I told the whole story with didn't seem to care. - CORRECT

The police officer with who I told the whole story didn't seem to care. - INCORRECT

That cannot go after a comma (,)

Example: Beethoven was a famous musician. He wrote Piano Sonata No.14.

Beethoven, who was a famous musician, wrote Piano Sonata No.14. - CORRECT

Beethoven, that was a famous musician, wrote Piano Sonata No.14. - INCORRECT

That cannot go after comma (,) + most of …, all of …, some of…, many of …, two of …

Example: The man has five daughters. Three of them are doctors.

The man has five daughters, three of whom are doctors. - CORRECT

The man has five daughters, three of that are doctors. - INCORRECT

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Related posts:

Relative Part 2 - That, Defining and Non-defining

Relative Part 3 - Whose, When, Where