6 Structuring a complex sentence
Complex sentences differ from compound sentences in that their meaning depends on the combination of the two clauses, one of which is incomplete because it cannot stand on its own.
Look at this example:
If children’s diets are low in energy
This clause contains a subject (children’s diets) and a predicate (are low in energy) but it cannot stand on its own because it starts with ‘if’. This type of clause is called a dependent clause because in order to be meaningful it needs to be joined to an independent clause.
For example:
| Dependent clause | Comma | Independent clause |
| If children’s diets are low in energy | , | they will stop growing and gaining weight. |
Now look at another example:
When people suffer from malnutrition, they are often deficient in the vitamins and minerals needed by the body.
As with the example using ‘if’, this sentence consists of two clauses, each of which includes a subject and a predicate. However, the first clause cannot stand on its own because it starts with ‘when’: it therefore needs to be joined to an independent clause to make sense. When the two sentences are joined, it is clear to the reader that it is only when people are deficient in the vitamins and minerals needed by the body that they may suffer from malnutrition.