Complex sentences

A complex sentence is formed by adding one or more subordinate (dependent) clauses to the main (independent) clause using conjunctions and/or relative pronouns. A clause is a simple sentence. Simple sentences contain only one clause (verb group). Complex sentences contain more than one clause (verb group).

In technical, scientific and mathematical writing the logical relationship between the items that the conjunctions connect is not made explicit and introduces comprehension complications. These writing genres bring the challenging elements of unfamiliar vocabulary including jargon and technical words, lexically dense sentences and an element of ‘guessing’ or interpreting the data in relation to the task. For many students the concepts or subject matter are unfamiliar and therefore problematic, for example:

Verbs

1. The ice melts as the temperature rises. Students have to interpret causality in the sentence “The ice melts as the temperature rises, " meaning that the events happen simultaneously and the rise in temperature causes the ice to melt.
2. The sugar dissolves when placed in water. This means that the sugar dissolves when it is placed in water because water is a solvent. Here the ellipsis of it is’ increases the difficulty for students.

None of these meanings is made explicit but has to be ‘recovered’. Causality has to be inferred from the sentences using the student’s knowledge of grammar and the water acting as a solvent has to be inferred from students’ contextual knowledge of the subject.

Constructing complex sentences

Complex sentences result when other more sophisticated devices are used to join clauses; this means a subordinate (dependent) clause is joined with a main (or independent) clause.

There are three main ways to join clauses to make complex sentences. By using:

• relative pronouns – that, which, who, whose.
• conjunctions (subordinating) – while, because, although, as, when, until, unless, through, by, since, whenever, if, where, before and so on.
• verb structures (non-finite) – (participle) verb forms that end in –ing or –ed or an infinitive verb form such as to go, to become, to see.