Complex Sentences Lesson

Complex Sentences

Band 8+ writing uses a controlled mix of dependent and independent clauses. This lesson shows the four patterns examiners look for.

Why complex sentences matter

The public band descriptors reward candidates who use ‘a variety of complex structures’ with ‘frequent error-free sentences’. That means combining ideas with subordinators (although, because, while, whereas) and non-defining relative clauses rather than stacking short simple sentences.

Four go-to patterns

1) Subordinator + main clause: ‘Although the policy is popular, its long-term impact is uncertain.’ 2) Main clause + non-defining relative clause: ‘The policy, which was introduced in 2022, has already reduced emissions.’ 3) Participle phrase opener: ‘Driven by rising costs, many families have relocated.’ 4) Cleft sentence for emphasis: ‘What matters most is how the funds are spent.’

Common mistakes vs. correct IELTS usage

Common mistake

"Many people use cars. This causes pollution. Governments should act."

Band 8+ version

"Because private cars are a major source of urban pollution, governments have a clear obligation to intervene."

Combine three short sentences into one subordinated structure.

Common mistake

"The plan is good. It has some problems."

Band 8+ version

"The plan, although broadly sound, has several implementation issues."

A non-defining relative or concessive clause adds precision.

Mini quiz · 3 questions

1. Which sentence best combines: ‘Cities are growing. Public transport is inadequate.’

Cities are growing and public transport is inadequate. Although cities are growing rapidly, public transport remains inadequate. Cities growing, public transport not enough.

‘Although’ subordinates the first clause and creates a genuine complex sentence.
2. Identify the non-defining relative clause.

The students who studied hardest scored highest. The reform, which passed last year, is now under review. The book that I borrowed was excellent.

Non-defining relative clauses are set off by commas and add extra, non-essential information.
3. Which is a participle phrase opener?

Because he was tired, he stopped working. Exhausted by the journey, he collapsed on the bed. He was so tired that he stopped.

‘Exhausted by the journey’ is a past-participle phrase acting as an opening adverbial.

← All lessons

Articles (a / an / the)

Article errors are the single most common grammar issue in IELTS writing. Master three rules and most mistakes disappear.

The three-question test

Before every noun ask: (1) Is it countable and singular? If so, it needs an article. (2) Is it specific — known to the reader? Use ‘the’. (3) Is it a first mention or a general example? Use ‘a/an’.

Common IELTS traps

No article with plural or uncountable nouns in general statements: ‘Governments should invest in education’ (not ‘the governments’, not ‘the education’). Use ‘the’ with unique or previously mentioned things: ‘the environment’, ‘the government of Japan’.

Common mistakes vs. correct IELTS usage

Common mistake

"The pollution is a serious problem in the modern cities."

Band 8+ version

"Pollution is a serious problem in modern cities."

General ideas take no article; ‘cities’ is a plural general noun.

Common mistake

"Government should invest more in education."

Band 8+ version

"The government should invest more in education."

‘The government’ refers to a specific known institution.

Mini quiz · 3 questions

1. Choose the correct sentence.

The children need the good education. Children need a good education. The children need a good education.

General statement about children in general → no ‘the’; ‘education’ takes ‘a’ when modified by an adjective.
2. Fill the gap: ‘___ internet has transformed how we learn.’

A The (no article)

‘The internet’ is treated as a unique entity and always takes ‘the’.
3. Which is correct?

Most of people prefer working from home. Most people prefer working from home. The most people prefer working from home.

‘Most’ + plural noun without an article expresses a generalisation.

← All lessons

Subject–Verb Agreement

In long, complex sentences it is easy to lose track of the true subject. This lesson isolates the patterns that trip up Band 7 writers.

Find the head noun

The verb agrees with the head of the subject noun phrase, not the closest word. ‘The number of tourists visiting the region has risen’ — the subject is ‘the number’ (singular), not ‘tourists’.

Tricky quantifiers

‘A number of X’ takes a plural verb; ‘the number of X’ takes a singular verb. ‘Each’, ‘every’, ‘neither’ and ‘either’ take singular verbs even when followed by plural nouns.

Common mistakes vs. correct IELTS usage

Common mistake

"The number of applicants have doubled."

Band 8+ version

"The number of applicants has doubled."

The head noun is ‘number’, which is singular.

Common mistake

"Each of the students have their own laptop."

Band 8+ version

"Each of the students has their own laptop."

‘Each’ is singular.

Mini quiz · 3 questions

1. Choose the correct verb: ‘A number of students ___ concerned.’

is are has

‘A number of’ is plural in meaning.
2. Which sentence is correct?

The list of items are on the desk. The list of items is on the desk. The list of items were on the desk.

The subject is ‘list’, not ‘items’.
3. Choose the correct form: ‘Neither the students nor the teacher ___ arrived.’

have has were

With ‘neither … nor’, the verb agrees with the closer subject — here, singular ‘teacher’.

← All lessons

Relative Clauses

Relative clauses let you pack more information into a sentence without losing clarity — a fast route to lifting your grammar score.

Defining vs non-defining

Defining clauses identify which one (‘The students who study daily improve fastest’) — no commas. Non-defining clauses add extra information about a known noun (‘Cambridge, which is world-famous, publishes the exam’) — always with commas.

Choosing the right pronoun

‘Who’ for people, ‘which’ for things, ‘that’ only in defining clauses. Use ‘whose’ for possession and ‘where’ for places. In formal writing avoid dropping the pronoun.

Common mistakes vs. correct IELTS usage

Common mistake

"The policy that was introduced in 2022, has reduced emissions."

Band 8+ version

"The policy, which was introduced in 2022, has reduced emissions."

Non-defining clause needs commas and ‘which’, not ‘that’.

Common mistake

"Students which work hardest succeed most."

Band 8+ version

"Students who work hardest succeed most."

Use ‘who’ for people.

Mini quiz · 3 questions

1. Choose the correct pronoun: ‘My teacher, ___ speaks four languages, is very inspiring.’

that which who

‘Who’ is required for people in non-defining clauses.
2. Which sentence uses commas correctly?

The book, that I bought, was expensive. The book which I bought was expensive. The book, which is on the shelf, is mine.

Non-defining clauses (extra information) are enclosed in commas.
3. Fill the gap: ‘This is the town ___ I grew up.’

which where that

‘Where’ refers to a place and functions as a relative adverb.

Sentence craft for Band 8+