Skip main navigation

New offer! Get 30% off one whole year of Unlimited learning. Subscribe for just £249.99 £174.99. New subscribers only. T&Cs apply

Find out more

Grammar: Complex sentences

Using correct grammar
Four young people chatting in a cafe

In previous steps, you have learnt about the different item types in the speaking section of PTE Academic and how oral fluency and the content you choose to include are important to successfully answer these. In this step, you will learn about how you can recognise complex grammatical structures in the items and use them in your responses.


A clause is a group of words which includes a subject and a verb. Clauses are the basic building blocks which we use to form sentences. There are two types of clauses: independent clauses and dependent clauses. Look at the following clauses. Are they independent or dependent clauses?

1) The graph is a bar graph. 2) Because it has developed.

Did you say that the first is an independent clause and the second a dependent clause? If so, you are correct. Do you know why?

Independent clauses contain a whole idea or express a complete thought which can stand alone. When we read the first sentence, it does not need further explanation.

Dependent clauses do not contain a whole idea or express a complete thought and cannot stand alone. When we read the second sentence, we need more information and wonder what has developed.

Simple sentences

Simple sentences contain one independent clause.

Compound sentences

Compound sentences contain two independent clauses linked by a coordinator in the middle of the sentence. The coordinators are for, and, not, but, or, yet, so.

Look at these examples of compound sentences and identify the relationship between the clauses. What is the meaning of the coordinator?

  • The number of people studying Spanish increased, but the number of people studying Russian decreased.

  • There were a number of trials so the researchers could determine the treatment’s effectiveness.

What did you think? Did you say that but shows contrast and so shows reason?

It is important to be able to recognise compound sentences in the item types as you should pause briefly between the two clauses. Read these sentences aloud with a short pause before the conjunction.

Complex sentences

Complex sentences are sentences which include an independent clause and a dependent clause linked by a subordinator. Look at the following sentence. Can you identify the subordinator and the dependent clause?

  • The bridge collapsed because the engineers failed to adequately reinforce it.

The subordinator used is ‘because. The dependent clause is the clause after this subordinator.

There are three types of dependent clauses which you can use to construct complex sentences, and they always begin with a subordinator. Let’s have a look at them.

Adverb clauses

Adverb clauses are clauses which function as adverbs in sentences. They are used to add detail to the action (i.e. verb) of the independent clause by saying how, why, when or where it occurs. Main types of adverb clauses

Type Relationship Subordinators
time when an event occurs before, after, as, when, while
reason/cause why an event occurs because, as, since
purpose why an event occurs so that, in order that
condition how an event occurs if, whether, unless
concession/contrast opposition even though, although

Adjective clauses

Adjective clauses are clauses which function as adjectives. They are used to provide extra information about nouns.

Main types of adjective clauses

Type Nouns described Example
which/that things The project’s objective is to maintain real-time solar wind monitoring, which is crucial for weather alerts and forecasts.
who/whom people What is someone who doesn’t eat any meat called?
where places The largest changes can be seen in Brisbane and Canberra where the average work day increased by 20 minutes.
when times The day when the explosion happened was a rainy day.
why reasons The reason why the class was cancelled was the teacher’s illness.
whose belongings The student whose essay was late lost 10 percent of their grade.

Noun clauses

Noun clauses are clauses which function as nouns. They can be subjects of sentences, objects of sentences, or objects of prepositions.

Main types of noun clauses

Type Relationships Example
that things He said that these are used in advertisements.
how manners Scientists are still not sure how to solve the issues with the experiment.
what things We need to know what the company is going to do.
who people It isn’t clear who will be negatively impacted.
if/ whether options We still don’t know if the drug is safe for humans.
why reasons It must also outline why the existing behaviour is detrimental to the viewer’s health.
when time We are not sure when the project will start.


Conditionals are complex sentences which use the subordinator if.

There are four main types of conditionals and they differ depending on the time (past, present or future) and on how likely the event or state is.

Look at the following examples. What is the structure of each type? What type of event does each type discuss?

Zero conditional

If a student fails the course, they do not progress to the next level.

First conditional

If the book is returned late, you will receive a fine.

Second conditional

If I had more time, I would edit my essay again.

Third conditional

If the student hadn’t handed the essay in late, he wouldn’t have failed.

How did you go? Let’s see how can you make each type of conditional.

Note: The if clause can be the first clause in the sentence or the second clause.

conditional if clause main clause example use
zero present simple present simple If you stand in the rain, you get wet. facts and truths
first present simple future If you study hard, you will pass. future possible events
second past simple would If I won the lottery, I would quit my job. future unlikely events
third past perfect would + have If I hadn’t copied, I wouldn’t have lost marks. past impossible events
© Macquarie University
This article is from the free online

Practise your PTE Academic Speaking Skills

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now