Relative pronouns: who, which, that, whose and whom

The commas tell the reader whether the clause identifies the noun or just adds information. Changing the commas can change the meaning.

In a defining clause about a thing, British English uses both: "the book which I borrowed" and "the book that I borrowed" are both correct. That is more common in speech; which is common in formal British writing.

Many American style guides ask writers to use that in defining clauses and to keep which for non-defining clauses with commas. This is a style preference, not a rule of British grammar.

That is usually preferred after everything, nothing, all, something and superlatives: "everything that he said", "the best film that I have seen".

In a non-defining clause, only which is possible for things: "The museum, which opened in 1990, is free." A comma followed by that is always wrong.

In formal writing, the preposition can go before whom or which: "the person to whom I spoke", "the house in which I grew up". In everyday English, it goes at the end: "the person I spoke to", "the house I grew up in".

Never put a preposition before that or who: say "the company for which she works" or "the company that she works for", not "the company for that she works".

Which can also refer to a whole idea, after a comma: "Prices fell, which helped first-time buyers."

• Wrong: The people which live here are friendly.

  Right: The people who live here are friendly.

  Use who, not which, for people.

• Wrong: My sister, that lives in Dubai, is a doctor.

  Right: My sister, who lives in Dubai, is a doctor.

  That can't begin a non-defining clause with commas.

• Wrong: This is the hotel in that we stayed.

  Right: This is the hotel in which we stayed. / This is the hotel that we stayed in.

  A preposition can't come before that.

• Wrong: The student whose his phone rang left the room.

  Right: The student whose phone rang left the room.

  Whose already shows possession, so don't add his.

• Wrong: Students, who study every day, improve faster.

  Right: Students who study every day improve faster.

  With commas, the sentence says all students study every day. Without them, it means only those students.

In IELTS Writing Task 1, a non-defining clause with which lets you add a comment on a figure: "Sales reached 40%, which was the highest figure in the period." In Task 2, Speaking and PTE Write Essay, relative clauses help you join ideas into complex sentences, which is part of grammatical range. Check every comma: a wrong comma can change who you are talking about.

Try each one, then open it to check your answer.

1. 1. Choose: "The engineer (who / which) designed the bridge won an award."

   who

   An engineer is a person.

2. 2. Choose: "Mumbai, (that / which) is India's largest city, is by the sea."

   which

   The clause is non-defining, so that isn't possible.

3. 3. Complete this: "That's the author ___ book I lent you."

   whose

   The book belongs to the author.

4. 4. Formal or informal? "the manager to whom I wrote"

   Formal.

   Putting the preposition before whom is typical of formal writing.

5. 5. Can you leave out the pronoun? "The course that I chose was hard."

   Yes: The course I chose was hard.

   That is the object of chose, so it can be dropped in a defining clause.

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