Day 125: Items in a series need to be structurally parallel.

Items in a series may be single words, phrases, clauses, or, even, entire sentences. These need to be written with a parallel, or same, grammatical structure. For example, all the items need to be adjectives, or all the items need to start with a present tense verb.

This is important for two reasons.

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First, it is correct. If you have different types of items in a series, the sentence is incorrect. This type of error is called, appropriately enough, a parallelism problem. Readers who notice the parallelism problem will discredit your authority on the topic—and your professionalism.

Second, parallel structures create a strong impact on the reader. If you have different types of items, you will damage the impact of the statement, potentially resulting in the opposite effect—the loss of professional credibility.

Let’s look at several examples of non-parallel structures and possible revisions.

Wrong: “The expected results are impact, credibility, and making a good impression.”
Right: “The expected results are impact, credibility, and a good impression.”

Wrong: “I am sure that he is guilty. I am sure that he is the culprit. And I am sure of these facts.”
Right: “I am sure that he is guilty. I am sure that he is the culprit. And I am sure that these facts are correct.”

Wrong: “A query letter should describe the contents of the book and why you think people will read it.”
Right: “A query letter should describe the contents of the book and discuss why you think people will read it.”