Understanding Relative Clauses Pt. 2 (defining and non-defining)

Grammar Explanations

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You know your who, which and that. Now let's tackle one of the trickiest parts of relative clauses — the difference between defining and non-defining clauses — plus whose, where, when, and when you can drop the pronoun altogether.

Defining vs. Non-Defining Relative Clauses

This is a crucial distinction!

Defining Relative Clauses (Essential Information)

The relative clause is ESSENTIAL to identify which person or thing we're talking about. Without it, the sentence loses its meaning. No commas.

  • The woman who lives next door is a doctor. (which woman? the one who lives next door)
  • Students who work hard succeed. (which students? the ones who work hard)
  • The car that I bought is red. (which car? the one I bought)

Remove the clause and the meaning falls apart: "The woman is a doctor" — which woman? We don't know.

Non-Defining Relative Clauses (Extra Information)

The relative clause adds EXTRA information but is not essential. The sentence is already clear without it. Use commas — this is very important!

  • My sister, who lives in Paris, is a doctor. (I have one sister — just adding extra info)
  • The Eiffel Tower, which was built in 1889, is in Paris. (we know which tower — extra info)
  • John, who speaks five languages, got the job. (we know who John is — extra info)

Key Differences at a Glance

FeatureDefiningNon-Defining
CommasNOYES (essential!)
Essential?YesNo (extra info)
Can use "that"?YesNo — never!
Can omit pronoun?Sometimes (object)Never

Compare these two:

  • Defining: My brother who lives in London is a doctor. (I have more than one brother — specifying which one)
  • Non-defining: My brother, who lives in London, is a doctor. (I have one brother — just extra info)

One comma changes the whole meaning!

Remember: "That" can never be used in non-defining clauses:

  • ❌ My sister, that lives in Paris, is a doctor.
  • ✅ My sister, who lives in Paris, is a doctor.

When You Can Omit the Relative Pronoun

Good news — you don't always have to say it! When the relative pronoun is the object of the clause, you can leave it out (in defining clauses only).

Object = Can Omit ✅

  • The book that I bought is interesting. → The book I bought is interesting. ✅
  • The woman who I met was very nice. → The woman I met was very nice. ✅
  • The car which you saw is mine. → The car you saw is mine. ✅

Subject = Cannot Omit ❌

When the relative pronoun is the subject, you MUST keep it:

  • The book that is on the table is mine. ✅ (must keep)
  • ❌ The book is on the table is mine. (wrong!)

How to tell the difference:

  • Subject: relative pronoun + verb → who broke, which is, that crashed
  • Object: relative pronoun + subject + verb → who I met, which you saw, that he bought

WHOSE, WHERE & WHEN

WHOSE — For Possession

"Whose" shows possession — think of it like "his," "her," or "its" inside a relative clause.

  • The man whose car was stolen called the police. (= his car was stolen)
  • I know a woman whose daughter is a famous actress. (= her daughter)
  • The company whose products we use is very successful. (= its products)

Pattern: whose + noun (always)

WHERE — For Places

"Where" is used for places and replaces a preposition + which/that.

  • The hotel where we stayed was excellent. (= the hotel that we stayed at)
  • This is the restaurant where we first met. (= the restaurant that we first met in)
  • The city where I was born is very small.

WHEN — For Times

"When" is used for times. In modern English, it's often omitted or replaced with "that."

  • Do you remember the day when we first met?
  • 2020 was the year when everything changed.
  • The day when we met = The day that we met = The day we met ✅ (all fine!)

Quick Reference: whose, where, when + omitting pronouns

PronounUse forExample
whosePossessionThe man whose car was stolen...
wherePlacesThe hotel where we stayed...
whenTimes (often omittable)The day when we met...
(omit)Object in defining clauseThe book __ I bought... ✅

Practice

Add commas if needed:

  1. My brother who lives in Berlin is a doctor. [I have one brother]
  2. Students who study hard usually succeed. [which students? — defining]
  3. The Eiffel Tower which was built in 1889 is in Paris. [famous landmark — we know which one]

Can you omit the relative pronoun?

  1. The movie that we watched was good. → _______
  2. The man who lives here is my friend. → _______

Choose whose, where, or when:

  1. The hotel _______ we stayed was excellent.
  2. Do you remember the day _______ we first met?
  3. The man _______ car was stolen called the police.

Answers

  1. My brother, who lives in Berlin, is a doctor. (commas needed)
  2. Students who study hard usually succeed. (no commas — defining)
  3. The Eiffel Tower, which was built in 1889, is in Paris.
  4. Yes — The movie we watched was good. ✅
  5. No — "who lives here" is the subject, must keep it.
  6. where
  7. when
  8. whose

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