Punctuation · Parenthesis
Drop extra information in — then take it back out
Parenthesis means extra information added into the middle of a sentence. You can mark it off in three ways — with a pair of brackets ( ), a pair of dashes –, or a pair of commas ,. The golden rule: whatever you open with, you must close with the same, and the sentence must still make sense if you lift the extra part out.
Rule 1 Parenthesis always comes in a PAIR
The extra information needs a mark on both sides — two brackets, two dashes, or two commas. You can't open with one type and close with another.
My cousin (who is six) loves dinosaurs. ✓
✗ My cousin (who is six, loves dinosaurs. — opened with a bracket, closed with a comma.
Rule 2 The "lift-out" test
If you remove the words between the marks, the sentence should still make complete sense.
The cake, which Mum baked, was delicious. → The cake was delicious. ✓
That test tells you that the part in the middle really is parenthesis.
Rule 3 Brackets ( ) — the quietest
Brackets tuck information away most discreetly, often a fact, a date or an aside.
Mount Everest (the world's tallest mountain) is in Nepal. ✓
The full stop stays outside the bracket when the bracket is inside a sentence.
Rule 4 Dashes – the most noticeable
A pair of dashes adds emphasis or a dramatic aside — it stands out more than commas or brackets.
The winner – and nobody expected this – was the youngest runner. ✓
Use a dash on each side, just like the other pairs.
Rule 5 Commas , — the gentlest
A pair of commas is the smoothest way to add extra information into a sentence.
My teacher, Mrs Khan, is very kind. ✓
Trap: you still need both commas — a single comma leaves the parenthesis "open".
Match them Same on both sides
Whatever opens the parenthesis must close it. These pairings are correct:
( … ) · – … – · , … , ✓ mixed pairs like ( … , or , … ) are ✗
The 30-second method
How to crack any parenthesis MCQ fast
- Find the extra information — the part you could remove.
- Check it's wrapped in a PAIR — two of the same mark, one at each end.
- Do the lift-out test — read the sentence without the middle. Still make sense? Good.
- Match the marks — reject any sentence that opens with one mark and closes with another.
- One comma only? That's a half-finished parenthesis — wrong.
10 worked examples
Read the sentence, then the answer with the rule that solves it.
1. My dog a spaniel loves walks.
My dog, a spaniel, loves walks. — a pair of commas around the extra information (Rule 5).
2. The Nile the longest river is in Africa.
The Nile (the longest river) is in Africa. — brackets for a quiet fact (Rule 3).
3. Is this right? My uncle (a pilot, flies jets.
No — it opens with a bracket but closes with a comma. Marks must match (Match them).
4. Sam my best friend is moving away.
Sam, my best friend, is moving away. — a comma pair (Rule 5).
5. Lift-out test on The book, which was old, smelt musty.
The book smelt musty. — still makes sense, so the commas mark parenthesis (Rule 2).
6. The result and this shocked everyone was a draw.
The result – and this shocked everyone – was a draw. — dramatic dashes (Rule 4).
7. Is this right? Our school, founded in 1880) is old.
No — a comma can't be closed by a bracket. Use two commas or two brackets (Match them).
8. Paris the capital of France is beautiful.
Paris, the capital of France, is beautiful. — comma pair (Rule 5).
9. How many commas are needed in My gran who is 80 still swims.
Two: My gran, who is 80, still swims. (Rule 1).
10. The film it lasted three hours was boring.
The film – it lasted three hours – was boring. (or brackets/commas) — a matched pair (Rules 1 & 4).