Complex sentences and subordination

Build accurate complex sentences with subordinate clauses, participle clauses and fronted adverbials to widen your grammatical range.

All grammar rules

Marking criterion: Grammatical Range and Accuracy
Where it pays off: Writing Task 2 · Writing Task 1 · Speaking Part 3

Band descriptors for Grammatical Range and Accuracy ask for a variety of complex structures used with control. That means variety, not length. A complex sentence is simply one containing a subordinate clause; three well-controlled complex sentences per paragraph is plenty, and one accurate complex sentence outscores three sprawling ones held together by commas.

The four subordinators that do most of the work

Concession, cause, condition and time cover the great majority of academic argument. Learn to punctuate all four in both orders.

Concession: although, even though, while, whereas. 'Although public transport is cheaper, many commuters still drive.'
Cause: because, since, as, given that. 'Because fees have risen, enrolment has fallen.'
Condition: if, unless, provided that, as long as. 'Unless emissions fall, the target will be missed.'
Time: when, before, after, once, until. 'Once the subsidy ended, demand dropped sharply.'

Punctuate the two orders correctly

When the subordinate clause comes first, it takes a comma. When it comes second, it usually does not.

'Although costs rose, output improved.' Comma required.
'Output improved although costs rose.' No comma.
Never write 'Although costs rose, but output improved.' English uses one connector, not two.

Participle clauses add range cheaply

A participle clause compresses two ideas into one sentence and reads as naturally academic when the subject of both halves is the same.

'Having introduced the levy, the city saw traffic fall by a fifth.'
'Faced with rising costs, many families reduced their energy use.'
Keep the subjects matched. 'Walking to the station, the rain started' is a dangling participle and is wrong.

Do not confuse complexity with length

Comma splices and run-on sentences are accuracy errors, not range. If two clauses can each stand alone, they need a full stop, a semicolon, or a coordinating conjunction with a comma.

Wrong: 'Cities are growing, this creates pressure on housing.'
Right: 'Cities are growing, which creates pressure on housing.'
Right: 'Cities are growing; this creates pressure on housing.'
Clarity outranks ambition. If the reader has to go back to the start of your sentence to work out what it means, the sentence has cost you more than it earned.

Corrected examples

Incorrect: Although the policy was expensive, but it reduced congestion.

Correct: Although the policy was expensive, it reduced congestion.

Do not pair 'although' with 'but'. One subordinator is enough.

Incorrect: Because of the government invested in rail, journeys became faster.

Correct: Because the government invested in rail, journeys became faster.

'Because of' takes a noun phrase; 'because' takes a clause with a verb.

Incorrect: Fees increased, students dropped out.

Correct: As fees increased, students dropped out.

Two independent clauses joined by a comma is a comma splice. A subordinator fixes it and adds range.

Quick checklist

Aim for a natural mix of simple, compound and complex sentences.
Comma when the subordinate clause comes first; no comma when it comes second.
Never use 'although' and 'but' in the same sentence.
Check participle clauses share their subject with the main clause.

Apply it to a real response and check the length and structure.

Open the writing checklist