## Learning Outcomes

After reading this article, you will be able to construct and control complex sentences that accurately express ideas in IELTS Writing tasks. You will understand how to use subordination, relative clauses, and connectives to combine and contrast information, and apply correct punctuation and grammar to avoid common errors with clauses. You will also know key vocabulary to use in sophisticated sentence structures.

## IELTS Academic, General & UKVI Syllabus

For IELTS, you are required to demonstrate a range of sentence structures and clear control over complex sentences in your writing. For revision, focus on these syllabus points:

- Use a variety of sentence types, especially complex and compound-complex sentences, in both tasks.
- Correctly construct subordinate and relative clauses to add explanation, detail, and conditions.
- Employ linking words and conjunctions to compare, contrast, and show relationships between ideas.
- Punctuate and arrange clauses accurately to avoid run-ons and fragments.
- Avoid repetitive or simplistic sentence patterns by varying your structures.
- Use advanced vocabulary appropriate for complex sentences and relative clauses.

## Test Your Knowledge

_Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, look more closely at that area during your revision._

1. What is the difference between a compound sentence and a complex sentence?
2. Which of these sentences contains a relative clause:
   a) The book is new.
   b) The book that I bought is new.
3. True or false: It is correct to write two independent clauses joined only by a comma.
4. Give an example of a subordinating conjunction that introduces a reason.

## Introduction

IELTS Writing tasks reward candidates who use a wide variety of sentence types with accurate grammar. Complex sentences—those containing one main clause and at least one subordinate clause—allow you to express relationships between ideas, add specific details, and show contrast, reason, or time. Becoming proficient in these structures is essential to achieve a higher band for grammatical range and accuracy.

> **Key Term: Complex Sentence**
> A sentence that includes a main (independent) clause and at least one subordinate (dependent) clause.
> **Key Term: Clause**
> A group of words containing a subject and a verb, which can be independent (main) or dependent (subordinate).

### Why Use Complex Sentences in IELTS Writing?

Complex sentences demonstrate the ability to connect information and develop arguments clearly. They allow you to:

- Express reasons and results (e.g., because, so that).
- Show contrast or concession (e.g., although, even though).
- Indicate time or sequence (e.g., when, after, before).
- Add descriptive detail (e.g., who, which, where).
- Compare two or more ideas or situations.

IELTS examiners expect you to use a variety of these structures naturally, not just memorised patterns.

> **Key Term: Subordination**
> The use of a subordinate (dependent) clause to add extra information, detail, or conditions to a main clause.
> **Key Term: Relative Clause**
> A type of clause starting with 'who', 'which', 'that', 'where', or 'whose' that provides more information about a noun.

### Constructing Complex Sentences

A complex sentence consists of a main clause and one or more subordinate clauses. You can combine ideas by using subordinating conjunctions or relative pronouns.

![Complex sentence punctuation rules for subordinate and relative clauses, showing comma use according to clause position and defining versus non-defining function.](https://static.pastpaperhero.com/images/ielts-grammar-and-vocabulary-for-writing-complex-sentences-and-clause-control_00.png)

_Clause order and relative clause type determine whether commas follow an initial subordinate clause, set off non-defining clauses, or are omitted._

> **Key Term: Subordinating Conjunction**
> A linking word (e.g., because, although, if, when, since) that introduces a subordinate clause and shows its relationship to the main clause.

Common subordinate clause structures in IELTS:

- **Reason:** because, since, as
  (e.g., Many people use public transport because it is cheaper.)
- **Contrast:** although, even though, whereas
  (e.g., Although electric cars are expensive, they are better for the environment.)
- **Time:** when, after, before, while
  (e.g., When the results were published, the students celebrated.)
- **Purpose:** so that, in order to
  (e.g., The city widened the roads so that traffic would flow more smoothly.)
- **Condition:** if, unless, provided (that)
  (e.g., You will succeed if you practise regularly.)

**Relative clauses** add further detail to nouns:

- Defining: The people who live next door are very friendly.
- Non-defining: My brother, who lives in Oxford, will visit next week.

### Clause Types and Punctuation

**Main (independent) clause:** Can stand alone as a sentence.
**Subordinate (dependent) clause:** Cannot stand alone; adds information to the main clause.

Punctuation rules for complex sentences:

- Use a comma after a subordinate clause if it comes before the main clause.
  (e.g., If you work hard, you will pass the exam.)
- No comma is needed if the subordinate clause follows the main clause.
  (e.g., You will pass the exam if you work hard.)
- Commas separate non-defining (extra) relative clauses.
  (e.g., The museum, which was built in 1850, is still open.)

> **Key Term: Run-on Sentence**
> An error where two or more main clauses are joined incorrectly, usually without proper punctuation or conjunction.
> **Key Term: Fragment**
> An incomplete sentence that lacks a main clause, making it grammatically incorrect.

### Combining Clauses: Strategies

- **Subordination:** Use when the information in one clause is less important or supports the main idea.
- **Coordination (compound sentence):** Use 'and', 'but', 'or', 'nor', 'for', 'yet', 'so' to link equally important ideas.
- **Relative Clauses:** Attach to a noun to add essential or extra detail, improving coherence.

### Worked Example 1.1

Despite widespread efforts to encourage healthy eating in schools, many children continue to prefer food that contains high levels of sugar and fat. Researchers have found that although knowledge of nutrition is increasing among the younger generation, eating habits are shaped by advertising and availability. Therefore, experts suggest that improving education alone is insufficient if unhealthy food remains easily accessible.

Question:
Rewrite the bolded ideas in the paragraph above using at least one complex sentence with a subordinate clause and one relative clause.

> **Answer:**
> Although many children know about good nutrition, they continue to eat food that is high in sugar and fat, which is often advertised heavily. Experts suggest that improving education alone is insufficient if unhealthy food remains easily accessible.

### Worked Example 1.2

For centuries, cities have relied on public transport systems to reduce congestion and air pollution. Nevertheless, some commuters choose private vehicles regardless of traffic problems.

Question:
Combine these sentences into a single complex sentence using a subordinating conjunction.

> **Answer:**
> Although cities have relied on public transport systems for centuries to reduce congestion and air pollution, some commuters continue to choose private vehicles.

### Worked Example 1.3

In a recent study, university graduates were surveyed to determine whether living abroad improves job prospects. The results showed that graduates who had spent a year overseas reported higher employment rates.

Question:
Explain how the relative clause adds detail and avoids repetition.

> **Answer:**
> The relative clause "who had spent a year overseas" clearly states which graduates reported higher employment rates, making the sentence precise and informative.
>
> **Exam Warning:**
> A frequent error in IELTS Writing is joining two sentences with only a comma, which creates a run-on. Each main clause must be joined with a conjunction, relative clause, or correct punctuation.
>
> **Revision Tip:**
> When you finish writing, check that you use a mix of sentence types. Underline your complex sentences and check that each contains an appropriate clause and punctuation.

## Summary

Complex sentences and clause control allow you to combine, compare, and contrast ideas accurately in IELTS Writing. Correct use of subordination, relative clauses, and linking devices is needed for a high band score. Check punctuation and avoid run-on sentences and fragments.

## Key Point Checklist

_This article has covered the following key knowledge points:_

- Explain and identify complex sentences, main and subordinate clauses.
- Use subordinating conjunctions to express reason, contrast, time, purpose, and condition.
- Add detail using relative clauses, both defining and non-defining.
- Punctuate clauses accurately, including correct use of commas.
- Recognise and avoid run-on sentences and sentence fragments.
- Combine and contrast ideas flexibly for IELTS Writing Task 1 and Task 2.

## Key Terms and Concepts

- Complex Sentence
- Clause
- Subordination
- Relative Clause
- Subordinating Conjunction
- Run-on Sentence
- Fragment


Grammar and vocabulary for writing - Complex sentences and clause control