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Advanced Relative Clauses

1 min
C1
CEFR C1·clauses

Formula

(no comma)
(with commas)
: adds extra information

Examples

Positive
The book which I recommended is a bestseller.
Negative
Not applicable
Question
The architect whose designs won awards is coming to speak.

Usage

  • •Providing essential information to identify nouns
  • •Adding non-essential additional information
  • •Reducing clauses to more concise forms

More Examples

  • The students who passed the exam were given certificates.

    Defining: only those who passed (no commas)

  • The report, which took three months to write, was finally published.

    Non-defining: extra info, removable

  • The woman standing at the door is my manager.

    Reduced relative clause (who is standing → standing)

Common Mistakes

  • ✗❌ Using "that" in non-defining clauses: "My brother, that lives in Paris, …" → ✓ "…, who lives in Paris, …"
  • ✗❌ Missing commas in non-defining clauses: "My car which cost a fortune broke down" → ✓ "My car, which cost a fortune, broke down"
  • ✗❌ Reduced relative with the wrong participle: "The letter writing yesterday" → ✓ "The letter written yesterday" (passive = past participle)

Tips

  • ✓Defining clauses: no commas, can use "that". Non-defining: commas required, never use "that".
  • ✓Reduced relatives: active → present participle (the man running), passive → past participle (the letter written).

Advanced Notes

The comma distinction carries real meaning and is a common editing error even among advanced writers — remove the commas and the clause now restricts the noun; add them and it merely adds parenthetical information. "Whom" (object) is technically correct but sounds formal; "who" is widely accepted in speech. Reduced relatives allow elegant compression ("the report submitted last week") that characterises native-like academic prose. The sentential relative ("He ignored me, which upset her") comments on a whole clause, not a noun — a subtlety often missed at C1.

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Compare With

Participle Clauses(B2)Substitution and Ellipsis(C1)