Relative and Participle Clauses: Packing More into a Sentence
Defining and non-defining relatives, when to drop the pronoun, and the reduced clauses that make advanced English sound compact.
At C1 the difference between competent and fluent English is often density: how much you can attach to one noun without starting a new sentence.
Defining vs non-defining
Defining — tells you which one. No commas.
The report that we published in June has been withdrawn.
Remove it and you no longer know which report. The information is essential.
Non-defining — adds extra detail. Commas required.
The report, which we published in June, has been withdrawn.
There is only one report; the clause just adds a fact. The commas change the meaning, and this is the single most common C1 punctuation error.
My brother who lives in Berlin is a doctor. (I have several brothers.) My brother, who lives in Berlin, is a doctor. (I have one.)
Two rules follow: that cannot be used in non-defining clauses, and non-defining clauses can never be reduced.
Dropping the pronoun
In a defining clause, if the pronoun is the object, you can drop it:
The book (that) I ordered hasn't arrived. ✅ (object — droppable) The book that arrived was damaged. ✅ (subject — cannot drop)
Quick test: if a noun or pronoun follows immediately, it was the object, and you can drop it.
Prepositions
The colleague who I spoke to. (informal) The colleague to whom I spoke. (formal — the preposition moves to the front and forces whom)
Never to who. Once the preposition is fronted, whom is obligatory.
Whose, where, when
- the company whose licence was revoked (possession — works for things too)
- the year when the policy changed = in which
- the point where the argument fails = at which
Reduced (participle) clauses
Defining clauses with a continuous or passive verb can lose the pronoun and auxiliary:
The people who are waiting outside → the people waiting outside The measures that were introduced last year → the measures introduced last year
This is what makes formal English so compact:
Applicants submitting incomplete forms will be contacted. Funds allocated to the scheme remain unspent.
The trap: the participle must belong to the noun it sits next to.
❌ Having reviewed the data, the conclusion was obvious. (the conclusion reviewed nothing) ✅ Having reviewed the data, we found the conclusion obvious.
Test yourself
The quiz below covers commas, droppable pronouns, fronted prepositions and reduction.