Clauses & Phrases Intermediate

Relative Clauses

Master English relative clauses. Learn the difference between defining and non-defining relative clauses, when to use who/which/that/where, correct punctuation, and how to use them in PTE and IELTS writing.

What is Relative Clauses?

Relative clauses (also called adjective clauses) provide information about a noun using relative pronouns: who, whom, which, that, whose, where, when. The key distinction is between defining (restrictive) clauses that identify the noun, and non-defining (non-restrictive) clauses that add extra information with commas.

Rules & Formation

Defining (restrictive): identifies which specific thing/person is meant. NO commas. "The student who scored highest was offered a scholarship."
Non-defining (non-restrictive): adds extra information about an already-identified noun. REQUIRES commas. "Professor Smith, who has published 30 papers, is leading the project."
Who/Whom: for people (who = subject; whom = object). "The researcher who conducted the study." / "The researcher whom they appointed."
Which: for things (non-defining). That: for things and people (defining only). "The study, which was published in 2020,..." / "The study that was published in 2020 [not: which]" (formal distinction — "that" preferred for defining).
Whose: possession for people and things. "A student whose score exceeded 79 will receive a distinction."
Where/When: for places and times. "The city where the study was conducted has a population of 2 million."

Examples

The approach that the researchers adopted proved highly effective. (defining — identifies which approach)

This methodology, which was first developed in the 1990s, is now widely used. (non-defining — extra info)

Students whose scores fall below 65 will need to resit the assessment.

The university where she completed her PhD is ranked in the global top 100.

The year when regulations were first introduced marked a turning point in the industry.

❌ The problem, that causes concern, ... → ✅ The problem, which causes concern, ... (non-defining needs "which")

🎯 Exam Tip — PTE & IELTS

In IELTS Writing Task 2, non-defining relative clauses demonstrate grammatical sophistication: "This approach, which has been adopted by numerous governments, has yielded mixed results." They embed information within sentences and show control of punctuation. In PTE Write Essay, using both types of relative clauses and correctly punctuating non-defining clauses signals C1-level grammar to the AI scoring engine.

Frequently Asked Questions

Can I use "that" instead of "which" or "who"?

"That" can replace "which" or "who" in DEFINING clauses only: "The policy that/which the government introduced..." / "The student that/who scored highest..." However, "that" CANNOT be used in non-defining clauses: "Professor Smith, who (not that) is the lead researcher,...". In formal academic writing, "who" for people and "which" for things in defining clauses is preferred. "That" is more informal.

Can I omit the relative pronoun?

Yes, in defining clauses where the relative pronoun is the OBJECT of the clause: "The report [that] she submitted was excellent." — "that" can be omitted because "she" is the subject, "report" is the object. You cannot omit the relative pronoun when it is the SUBJECT of the clause: "The report that [NOT omittable] was submitted..." — "that" is the subject here.

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