What is Parallel Structure?

This guide is unhelpful, lacks sound advice, and it must have been written by tree-dwelling apes.

What is wrong with this sentence, besides its unfairly low esteem for the writing guide? The wording just sounds clunky, doesn't it?

The main problem is a lack of parallel structure. The sentence makes three statements about its subject (This guide), but the statements are structurally very different. The first (is unhelpful) features a to be verb followed by an adjective. The second (lacks sound advice) has an action verb followed by a noun. And the third (it must have been written by tree-dwelling apes) begins with a pronoun (it) and contains a passive verb.

In a sentence with parallel structure, elements like these would all be phrased in a grammatically similar fashion. In a moment, I will invite you to revise the sample sentence above so that its three statements become parallel. But first, consider the sentence below and ask yourself: Does it use parallel structure or not?

Engineers designed the building, and its construction was overseen by them.

If you answered "No," you were right: the two clauses in this sentence are not parallel. In the first clause, "Engineers designed the building," the verb is active; in the second clause, "its construction was overseen by them," the verb is passive. Notice, too, that the subjects of the two clauses are different: Engineers in the first clause, construction in the second.

The first step in making the clauses parallel is to keep one subject throughout:

Engineers designed the building and oversaw its construction.

This sentence, with one subject and two active verbs, is both more concise and more forceful than the original. It has a rhythm and an emphasis that were missing in the earlier version.

Try One on Your Own!

How would you rewrite the sentence that starts this article? Type your answer in the box below, then click to see a suggested answer.

This guide is unhelpful, lacks sound advice, and it must have been written by tree-dwelling apes.

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Parallel Structure

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