Clauses are building blocks: sentences can have one or more. When they’re well structured, clauses give people clear information.

Clauses contain at least one verb

A clause is a group of words that contains a subject and a verb.

A clause can be:

  • a main clause
  • a subordinate clause – noun, adjectival or adverbial.

A main clause can usually stand alone as a sentence, but a subordinate clause can’t.

A main clause can stand alone as a sentence

Every sentence has at least one main clause. The main clause is also known as:

  • a principal clause
  • an independent clause.

The main clause has at least one complete (finite) verb and can stand alone as a sentence.


We will price the project accurately.

[The entire sentence is a main clause.]

When we know the final cost estimates, we will price the project accurately.

[The main clause is ‘we will price the project accurately’.]

A compound sentence contains 2 or more main clauses joined by a coordinating conjunction. Each clause has a complete verb and could stand on its own.


We will price the project accurately and it will finish on time.

[There are 2 main clauses in this sentence, joined by the coordinating conjunction ‘and’.]

Subordinate clauses depend on the main clause

A subordinate clause can’t stand alone as a sentence. Subordinate clauses depend on the main clause to make sense. This is why they are also called ‘dependent clauses’.

Types of subordinate clauses are:

  • noun clause
  • adjectival clause
  • adverbial clause.

Noun clauses

Noun clauses act as nouns in a sentence, even though they may consist of other types of words. You can replace a noun clause with ‘it’ and the sentence will still make sense.


How you are still working is a mystery. / It is a mystery.

[‘How you are still working’ is a noun clause.]

Noun clauses often start with a:

  • relative pronoun – such as ‘that’ or ‘who’
  • subordinating conjunction – such as ‘although’ or ‘because’.


That Canberra winters are cold is well known. / It is well known.

[‘That Canberra winters are cold’ is a noun clause.]

They can also start with a verb in its basic form, which means it has the word ‘to’ (such as ‘to sleep’, ‘to sit’).


He learned to Skype. / He learned it.

[‘To Skype’ is a noun clause.]

Adjectival clauses

An adjectival (or relative) clause acts as an adjective. It describes a noun.

Adjectival clauses are usually, but not always, introduced by a relative pronoun (such as ‘that’, ‘which’, ‘who’, ‘whom’, ‘whose’).

The sentence should still make sense if you remove the adjectival clause.


The office, which is in the city, closed for the day. / The office closed for the day.

[‘Which is in the city’ is an adjectival clause.]

This is the committee that met for 12 hours last Tuesday. / This is the committee.

[‘That met for 12 hours last Tuesday’ is an adjectival clause.]

The manager, whose staff work hard, often stays back late. / The manager often stays back late.

[‘Whose staff work hard’ is an adjectival clause.]

Adverbial clauses

Adverbial clauses stand in for adverbs. They describe time, place, manner, reason, condition, purpose or concession.

The sentence should still make sense if you remove the adverbial clause.


I always eat breakfast before I go to work. / I always eat breakfast.

[‘Before I go to work’ is an adverbial clause.]

Adverbial clauses are usually, but not always, introduced by:

  • a relative pronoun – such as ‘that’, ‘which’, ‘who’, ‘whom’, ‘whose’
  • a preposition.


  • I always check all my emails before I respond. [Adverbial clause of time]
  • Let’s meet where there are videoconferencing facilities. [Adverbial clause of place]
  • She works as well as any other staff member. [Adverbial clause of manner]
  • I’m late for work because I missed the bus. [Adverbial clause of reason]
  • I’ll dial into the meeting if the server is working. [Adverbial clause of condition]
  • Please approve the $20 expense so that I can pay for the stationery. [Adverbial clause of purpose]
  • Although the deadline was almost upon her, she had a rest during the weekend. [Adverbial clause of concession]

In the last example, the comma after the adverbial clause helps users find the subject in the sentence (‘she’).

In some sentences, the subject isn’t easy to find without the comma.


When I met with Eun-jung, Deng met with Evelyn.

[‘Deng’ is the subject of the main clause.]


When I met with Eun-jung Deng met with Evelyn.

[The adverbial clause is not marked with a comma, which obscures the main clause.]

Conjunctions ‘if’ and ‘whether’

‘If’ and ‘whether’ are both subordinating conjunctions. They can often be  interchangeable, particularly in spoken English. Yet they have different meanings. When you’re writing, choose the right one:

  • ‘If’ is conditional. It defines a condition that needs to exist for the main clause to be true.
  • ‘Whether’ shows 2 possibilities. Sometimes one of the possibilities can be understood rather than explicitly mentioned.


We can eat lunch outside if the rain stops.

[The condition for eating lunch outside is that the rain stops.]

We can choose whether to eat lunch outside or inside.

[There are 2 places to eat lunch.]

We asked whether the office was open [or not].

[The ‘or not’ is implied. The office could be open or not open.]

When there are 2 concrete possibilities, using ‘if’ instead of ‘whether’ can lead to ambiguous sentences.


We asked whether he was working from home or from the office.

[Was he working from home or was he working from the office?]

We asked if he was working from home or from the office.

[Was he working at all, regardless of the location?]

Release notes

The digital edition has practical guidance on plain language. It relates grammatical concepts to the principles of plain language.

The digital edition consolidates information from the sixth edition and highlights the basics about clauses. It takes a different approach to the sixth edition by breaking related topics into specific subject areas like ‘phrases’ and ‘types of words’.

The Content Guide did not have any in-depth information on grammatical concepts.

About this page


Altenberg EP and Vago RM (2010) English grammar: understanding the basics, Cambridge University Press, Cambridge.

Dixon JC and Bolitho B (2005–2019a) Course notes and exercises: English grammar for writers, editors and policymakers, Centre for Continuing Education, Australian National University, Canberra.

Dixon JC and Bolitho B (2005–2019b) Report writing, Centre for Continuing Education, Australian National University, Canberra.

European Commission (2020) English style guide: a handbook for authors and translators in the European Commission, European Commission.

Murphy EM (2011) Working words, Canberra Society of Editors, Canberra.

Murphy EM with Cadman H (2014) Effective writing: plain English at work, 2nd edn, Lacuna, Westgate.

Seely J (2001) Oxford everyday grammar, Oxford University Press, Oxford.

Stilman A (2004) Grammatically correct, Writer’s Digest Books, Ohio.

Strunk W and White EB (2000) The elements of style, 4th edn, Longman, New York.

Truss L (2003) Eats, shoots and leaves: the zero tolerance approach to punctuation, Profile Books, London.

This page was updated Wednesday 5 July 2023.

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