Sentence Structure and Clauses

A breakdown explanation of sentence structure, sentence clauses and how to use them to enhance your writing.

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Sentence structure and clauses are something that you don’t really ever pay attention to when you’re writing. However, if you’re finding that a sentence is confusing or is making the wrong point, it will often be because you haven’t correctly structured your sentence. Breaking it down into clauses can help you find where you’ve been going wrong.

Main Clause

As the name suggests, this is the main part of the sentence. Every sentence must have a main clause and, if it has a verb, each clause should only have the one to avoid verb confusion.

John likes fish.

This is a perfectly fine sentence in its own right. It has the verb like in it and the focus is very clear. This is the main clause’s job.

You can have more than one main clause in a sentence but this is achieved by using a conjunction such as and, or, but, or so. This is because, essentially, you are merging two sentences together. When you do this the two main clauses that you’re merging should be related.

John likes fish. John doesn’t like to eat fish.

John likes fish but John doesn’t like to eat fish.

This becomes a compound sentence and, because of the conjunction, it allows you to ignore the fact that you should only have one main clause per sentence.

Subordinate Clause

A subordinate clause doesn’t work on its own. It relies on the main clause for its meaning.

After I’d cleaned the fridge, I ate a sandwich.

The subordinate clause, after I’d cleaned the fridge, doesn’t make sense on its own but it adds some more information to the main clause, I ate a sandwich.

There are two main subsets of subordinate clauses: conditional and relative.

Conditional Clause

A conditional clause usually begins with if or unless and is used to describe something that is possible.

I’ll be at work on time unless there is traffic.

The conditional clause unless there is traffic, much like other clauses, adds extra information and is related to the main clause.

Relative Clause

A relative clause is connected to the main clause by a word like which, that, when, or where.

I saw Mother yesterday, when I was cooking dinner.

There are two types of relative clauses, however. The first is a restrictive relative clause and the other is a non-restrictive relative clause.

A restrictive relative clause is one that gives essential information to the main clause that it’s connected to. Without the restrictive relative clause, the sentence doesn’t make any sense.

People with dogs are wonderful.

The with dogs doesn’t make sense and without the main clause, and the main clause people are wonderful doesn’t make the point that you are trying to make.

A non-restrictive relative clause provides extra information that isn’t vital to the overall meaning.

Sally, who has a dog, is wonderful.

The main clause Sally is wonderful makes sense on its own, but the extra information adds something else to the overall sentence.


If you find that a particular sentence has lost its focus try breaking it up into its clauses and you’ll see why it doesn’t quite work. You should, apart from when using a conjunction, only ever have one main clause in your sentence and everything else needs to be relating to that single clause.

David Chitty was born and raised in Thanet in the 90s. He devotes most of his energies to writing fantasy fiction novels.

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