KNOWLEDGE BASICS
I. Defining relative clauses
Defining relative clauses carry essential information, because they identify which thing or person we are talking about, and they are used without commas.
- This is the music which was used at the show.
- Have they found the prisoner who escaped last week?
We can use that
In defining relative clauses we can use that instead of which or who.
- This is the music that was used at the show.
- Have they found the prisoner that escaped last week?
When can we omit who/which/that?
Who/which/that, can be omitted if they are followed by subject + verb
- Can you pass me the box (which/that) I keep in the top drawer?
- You are not the man (who/that) I thought you were.
Non-defining relative clauses
Non-defining relative clauses are used between commas, and they add extra information which is not necessary to know who or what we are talking about.
- This music, which I really like, was used at the show.
- My sister, who I truly admire, is coming for Thanksgiving.
We cannot use that, and we cannot omit who/which
In non-defining relative clauses (between commas) we cannot use that, and we cannot omit who/which.
- This music, that I really like, was used at the show.
- My sister, I truly admire, is coming for Thanksgiving.
II. Defining vs non-defining relative clauses
In a defining relative clause the information is essential to identify who or what we are talking about, whereas in non-defining relative clauses we just add extra the information, which is not necessary. Compare:
- My brother who lives in Cardiff is much older than me. (=I have more than one brother and the relative clause helps identify which brother I am talking about)
- My brother, who lives in Cardiff, is much older than me. (=I have only one brother, so we don’t need the relative clause to know who I am talking about)
III. Common mistakes
Two subjects
When who, which or that is the subject of a relative clause, we don’t use another pronoun or noun after it, because we can only have one subject (who, which or that).
- I saw a man who was very tall. (NOT:
I saw a man who he was very tall.)
- That is the painting that was stolen from the gallery. (NOT:
That is the painting that it was stolen from the gallery.)
that between commas
We cannot use the relative pronoun that in a non-defining relative clause (between commas)
- The victim, who suffered a concussion, said he didn’t remember the accident. (NOT,
The victim, that suffered a concussion, said he didn’t remember the accident.)
