2.2. Relative clauses

We use defining relative clauses to give essential information about someone or something – information that we need in order to understand what or who is being referred to. A defining relative clause usually comes immediately after the noun it describes.

We usually use a relative pronoun (e.g. who, that, which, whose and whom) to introduce a defining relative clause:

• They're the people who want to buy our house.
• They should give the money to somebody who they think needs the treatment most.

Subject or object

The relative pronoun can define the subject or the object of the verb:

• They're the people who/that bought our house. (The people bought our house. The people is the subject.)
• They're the people who/that she met at Jon's party. (She met the people. The people is the object.)

No relative pronoun
We often leave out the relative pronoun when it is the object of the verb:

• They're the people she met at Jon's party.
• Here are some cells the researcher has identified.

In writing, we don't use commas in defining relative clauses:

• This is a man who takes his responsibilities seriously.

Nouns and pronouns in relative clauses

 When the relative pronoun is the subject of the relative clause, we don’t use another personal pronoun or noun in the relative clause because the subject is the same:

• She’s the lady who lent me her phone. (who is the subject of the relative clause, so we don’t need the personal pronoun she)

Not: She’s the lady who she lent me her phone.

• There are now only two schools in the area that actually teach Latin. (that is the subject of the relative clause, so we don’t need the personal pronoun they)

Not: There are now only two schools in the area that they actually teach Latin.

When the relative pronoun is the object of the relative clause, we don’t use another personal pronoun or noun in the relative clause because the object is the same:

• We had a lovely meal at the place which Phil recommended. (which is the object of the relative clause, so we don’t need the personal pronoun it)

We use non-defining relative clauses to give extra information about the person or thing. It is not necessary information. We don't need it to understand who or what is being referred to.

We always use a relative pronoun (who, which, whose or whom) to introduce a non-defining relative clause.

• Clare, who I work with, is doing the London marathon this year.
• Doctors use the testing kit for regular screening for lung and stomach cancers, which account for 70% of cancers treated in the western world.

In writing, we use commas around non-defining relative clauses:

• Etheridge, who is English-born with Irish parents, replaces Neil Francis, whose injury forced him to withdraw last week.

Relative clauses referring to a whole sentence. Some relative clauses refer to a whole clause, a whole sentence, or a longer stretch of language. We always use which to introduce these clauses.

We often use these clauses in informal speaking to express an opinion or evaluation:

• I think the other thing that was really good about it as well was that everybody worked really hard and helped tidy up at the end, which I hadn't expected at all.

• What is the name of that boy who just walked in?

Here the clause 'who just walked in' is an example of a relative clause. It modifies the noun boy. Relative clauses are also called adjective clauses.

Relative clauses are sometimes shortened. How do we reduce a relative clause? A participle can often be used instead of a relative pronoun and full verb.
For example:

• The girl who sits next to Peter is my neighbor's daughter.

Now when we shorten the relative clause 'who sits next to Peter', we get:

• The girl sitting next to Peter is my neighbor's daughter.

Another example is given below:

• Who is the girl who is sitting next to your brother?

Now when we reduce the relative clause, we get:

• Who is the girl sitting next to your brother?

Reduced structures can also be used with the adjectives available and possible.

• Please book all the tickets available. (= Please book all the tickets that are available.)

Source: Englishgrammarorg. (2016). Englishgrammarorg. Retrieved 20 June, 2016, from http://www.englishgrammar.org/reduced-relative-clauses/ 

 Have fun practising!