Relative clause

It is important to distinguish between defining and non-defining relative clauses.

Defining relative clauses are an essential part of the meaning of a sentence and therefore they cannot be left out. They define exactly who or what we are talking about.
Ex: There’s the woman you where telling me about.

Non-defining relative clauses add extra information of secondary importance and can be left out of a sentence.
Ex: Mrs Hamouda, who was an extremely mean person while he was alive, has left all his money to a neighbour.

*Non-defining relative clauses are mainly found in written English, where sentence are carefully constructed. In spoken English, they sound rather normal and can easily be expressed by simple sentences.

Defining relative clauses

Here are the main forms used. The forms in brackets are possible but not as common.
Person thing
Subject Who (that) That (which)
Object --- (that) --- (that)

Notice that English has given the choice to put “that” or to omit it when the object of the clause id defined. It likes to drop it.

Ex: The doctor who helped me most was Dr. Brahmia (subject).
• The doctor I found most helpful was Dr. brahmia (object).
• The treatment I liked best was acupuncture (object).
• The treatment that helped me most was acupuncture (subject).

Notice that there are no commas before and after defining relative clauses when written and no pauses when spoken.
That is usually used after the following superlatives: all, every (thing), some (thing), any (thing), no (thing), and only.

Ex: he wrote some of the best poetry that’s ever been written.
All that’s needed is a little more time.
Don’t take anything that’s valuable.
The only thing that matters is that you are safe

• Prepositions can come either before relative pronouns or at the end of the relative clause. In spoken English, it is much more common to put the preposition at the end (and to drop the pronoun).

Ex: This is the book I was talking to you about.
The people I worked with are very kind.

A second relative introduction by and /or but usually takes a wh pronoun, not that.
Ex: Someone that I greatly admire, but who I’ve never met, is professor hellal.

Non-defining relative clauses

Here are the main forms used. The form in brackets is possible but not as common.
Person thing
Subject , who…, , which…,
Object , who…, (, whom…,) , which…,

Ex: Mr. Boudjedra, who has written several books, spoke at the meeting last night. (subject).
Ahmed Ouyahia, who Prime Minister, has become the leader of the RND Political party. (object).
My favourite dish is Couscous, which is the Algeria’s famous traditional dish. (subject).
I gave him a sandwich, which he ate greedily. (object).

Notice that unlike defining relative clauses, non-defining relative clauses are separated from their noun by commas. The pronoun can never be omitted in a non-defining relative clause. The construction is more common in written then in spoken English.