The officer that saw him speeding gave him a ticket.
or
The officer that gave him a ticket saw him speeding.
Notice that commas are not used with that. Look at a few more examples:
I like the girl.The girllives down that street.
I like the girl who lives down that street.
or
I like the girl that lives down that street.
He said a word. I don’t understand a word.
He said a word, which I don’t understand.
or
He said a word that I don’t understand.
Where’s the car? You bought the car.
Where’s the car that you bought?
or
Where’s the car you bought?
Let’s take a closer look at relative pronouns and the clauses they form.
English forms relative clauses in four ways:
- With the relative pronoun whoor whom, when referring to people.
Whois used as the subject of a sentence. Whomis used in all other
cases. Whosereplaces a possessive adjective (my, his, our, et cetera). - With the relative pronoun thatwhen referring to people or things.
- With the relative pronoun whichwhen referring to things.
52 Writing Better English