Complex sentences

Compound sentences contain two or more clauses of equal status. (They are all main clauses.) They are linked by co-ordinating conjunctions such as and or but. When clauses are linked in a different way we create something called a complex sentence. The term 'complex' describes the grammatical structure and not the length of the sentence or its complexity of meaning.

In a complex sentence, one clause is grammatically superior to the others. This clause is the main clause and any other clauses are subordinate to it. The best way to show how this works is to take a simple sentence and then turn it into a complex one.

Here we started with a subject that was a noun phrase and have substituted a clause for it, so that we end up with two clauses. Although a complex sentence has a main clause, this does not mean that the main clause is necessarily one that will stand alone if you pull it out of the sentence:

In a complex sentence subordinate clauses operate as clause elements for the main clause. So they can be the subject, object, complement, or adverbial.

There are three types of subordinate clause:

• Nominal clauses (sometimes called noun clauses)
  These can form the subject, object or complement
• Adverbial clauses
  As their name suggests, these function as adverbials
• Relative clauses
  These form part of a noun phrase.

©John Seely 2008