Relative clauses: who, which, that and commas

To move towards Band 7 in grammar, you need to show a range of complex sentences used with good control. Relative clauses are one of the easiest ways to show this, because they let you join two simple ideas into one clear sentence. But they also produce typical errors: wrong pronouns, missing or extra commas, and repeated subjects.

What is a relative clause?

A relative clause gives more information about a noun. It usually starts with who, which, that, whose, where or when.

• Two simple sentences: Rahim is a farmer. He grows organic vegetables near Bogura.
• One complex sentence: Rahim is a farmer who grows organic vegetables near Bogura.

Rule 1: Choose the right pronoun

• who → people: the teacher who inspired me

• which → things and animals: the bridge which connects the two districts

• that → people or things, but only in defining clauses (Rule 3)

• whose → possession: students whose parents work abroad

• where → places: the city where I was born

• when → times: the year when the metro rail opened

• ✘ The doctor which treated my mother was very kind.

• ✔ The doctor who treated my mother was very kind.

• ✘ Families who their income is low need support.

• ✔ Families whose income is low need support.

Rule 2: Do not repeat the subject or object

The relative pronoun already replaces the noun. Adding he, she, it or them again is one of the most common errors we see.

• ✘ The laptop which I bought it last year is already slow.
• ✔ The laptop which I bought last year is already slow.
• ✘ My cousin, who she studies in Penang, called me yesterday.
• ✔ My cousin, who studies in Penang, called me yesterday.

Rule 3: Defining clauses have no commas

A defining clause tells us which one. Without it, the sentence loses its meaning or becomes too general. Do not use commas, and you may use that.

• ✔ Students who work part-time often have less time to revise. (Only those students, not all students.)
• ✔ The course that I chose includes an internship.
• ✘ Students, who work part-time, often have less time to revise. (The commas now suggest that all students work part-time.)

In a defining clause, you can drop the pronoun if it is the object: The course I chose includes an internship.

Rule 4: Non-defining clauses need commas and never "that"

A non-defining clause adds extra information about something already identified. The sentence still works without it. Put commas on both sides (or a comma and a full stop), and use who or which, never that.

• ✔ Kuala Lumpur, which is the capital of Malaysia, attracts thousands of Bangladeshi students.
• ✔ My father, who retired last year, now spends his mornings in the garden.
• ✘ Dhaka, that is one of the most crowded cities in the world, needs better public transport.
• ✔ Dhaka, which is one of the most crowded cities in the world, needs better public transport.

Proper nouns (Dhaka, my father, the Padma Bridge) are already specific, so their relative clauses are almost always non-defining.

Rule 5: "which" can refer to a whole idea

A comma + which can comment on the entire previous clause. This is very useful in Task 2.

• ✔ Many graduates cannot find jobs in their field, which leads to frustration and brain drain.
• ✔ The price of rice rose by 30% in six months, which put pressure on low-income families.

Do not start a new sentence with Which: ✘ Many graduates cannot find jobs. Which leads to frustration.

Rule 6: Prepositions and reduced clauses (for Band 7+)

• Formal: the extent to which technology helps learning, the reasons for which people migrate

• Reduced: Students living in hostels (= who live), the data shown in the table (= which is shown)

• ✔ The figures given in the chart refer to 2022.

• ✔ Workers employed in the tourism sector were badly affected.

Use these carefully; a correct simple relative clause is better than an incorrect advanced one.

Mini exercise

Correct the errors. One sentence is already correct.

1. The garments industry which it employs millions of women is vital to Bangladesh's economy.
2. My uncle, that lives in Johor Bahru, runs a small restaurant.
3. People, who exercise regularly, tend to sleep better.
4. The graph shows the period when unemployment was highest.
5. Many young people move to cities. Which creates housing shortages.

Quick tip: Ask yourself, "If I delete this clause, do I still know who or what I am talking about?" If yes, use commas. If no, remove the commas. This single question solves most comma problems with relative clauses.

Answers

1. The garments industry, which employs millions of women, is vital to Bangladesh's economy. (remove "it"; non-defining because there is only one garments industry being discussed)
2. My uncle, who lives in Johor Bahru, runs a small restaurant.
3. People who exercise regularly tend to sleep better. (defining: no commas)
4. Correct.
5. Many young people move to cities, which creates housing shortages.