5 Types of Parallel-Structure Errors
Writers often have difficulty constructing sentences so that comparisons, contrasts, and lists, as well as parenthetical elements, are logically arranged. The following five sentences demonstrate various syntactical miscalculations; discussions and revisions follow each example.
1. Technology is transforming virtually every industry, changing not only how firms operate internally and engage their customers, but also challenging the underlying business models of entire industries.
When a single verb applies to both elements in a statement that employs a “not only . . . but also” construction, it must precede “not only.” Here, however, technology changes one thing and challenges another, so the two verbs are parceled out individually to “not only” and “but also” and must therefore follow those respective phrases: “Technology is transforming virtually every industry, not only changing how firms operate internally and engage their customers but also challenging the underlying business models of entire industries.”
2. He wasn’t aiming for realism but drama.
Here, a similar construction is necessary to convey a contrast. The conclusion in this sentence of “but drama” is an awkward, incomplete addition, and to be parallel, the negating adverb not must follow the verb phrase “was aiming” and the for preceding one noun must be matched by a duplicate before the other noun: “He was aiming not for realism but for drama.”
3. Like other social media companies, it uses a variety of tools, including spam-fighting technology, automatic identification as well as reports from users, to help combat abuse.
“As well as” is not a substitute for and as a link between the penultimate and final items in a list; it signals a transition from a list to a dependent clause (or, in this case, opens a parenthetical phrase, which is merely an interruptive dependent clause): “Like other social media companies, it uses a variety of tools, including spam-fighting technology and automatic identification, as well as reports from users, to help combat abuse.”
4. He made his mark both as a professional athlete and also as a philanthropist.
In this sentence (and in any sentence), and and also are redundant: “He made his mark both as a professional athlete and as a philanthropist.” (Both is not necessarily required, but it emphasizes the juxtaposition of a professional athlete also being a philanthropist.)
5. He’s kidnapped by a masked stranger, drugged, and awakes in an unknown facility.
For this sentence’s structure to be parallel, the matching verbs kidnapped and drugged must each have a helping verb (a form of “to be”—in this case, the contracted form of is), or and must replace the comma preceding drugged to indicate that it shares the helping verb with kidnapped: “He’s kidnapped by a masked stranger and drugged and awakes in an unknown facility.”
Note that the second comma has also been omitted; the phrase that begins with awakes—which, because it is in present tense, needs no helping verb—has no subject and is therefore not an independent clause, so no punctuation is required. (The grammatical rule against punctuating in such cases could be relaxed to imply a pause.)
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