18 | Parallel Structure
18|Parallel Structure
You use parallel structure, or parallelism, when you create a series of words, phrases, clauses, or sentences with the same grammatical form. The pattern created by the series—its parallel structure—emphasizes the similarities or differences among the items, whether things, qualities, actions, or ideas.
My favorite foods are roast beef, apple pie, and linguine with clams.
Louise is charming, witty, intelligent, and talented.
Manuel likes to swim, ride, and run.
Dave likes movies that scare him and books that make him laugh.
Each series is a perfect parallel construction, composed of equivalent words: nouns in the first example, then adjectives, verbs, and adjective clauses.
18aIn a series linked by a coordinating conjunction, keep all elements in the same grammatical form.
For more on coordination, see 19a–19c.
A coordinating conjunction (and, but, for, or, nor, so, yet) cues your readers to expect a parallel structure. Whether your series consists of single words, phrases, or clauses, its parts should balance one another.
Two elements in this series are parallel one-word adjectives (tiny, cute), but the third, the verb phrase clumsily bumping, is inconsistent.
Don’t mix verb forms, such as gerunds and infinitives, in a series.
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A gerund is a form of a verb, ending in -ing, that functions as a noun (see 8a).
An infinitive consists of the base form of a verb plus the word to (see 8a).
In a series of phrases or clauses, be sure that all elements in the series are similar in form, even if they are not similar in length.
18bIn a series linked by correlative conjunctions, keep all elements in the same grammatical form.
A correlative conjunction is a pair of linking words such as either/or or not only/but also that appear separately but work together to join elements of a sentence. When you use a correlative conjunction, follow each part with a similarly structured word, phrase, or clause.
Correlative Conjunctions at a Glance
| as . . . as | just as . . . so | not only . . . but also |
| both . . . and | neither . . . nor | whether . . . or |
| either . . . or | not . . . but |
18cMake the elements in a comparison parallel in form.
For more on comparisons, see 16a–16d and 16g.
A comparative word such as than or as cues the reader to expect a parallel structure. This makes logical sense: to be compared, two things must resemble each other, and parallel structure emphasizes this resemblance.
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18dReinforce parallel structure by repeating rather than mixing lead-in words.
Parallel structures are especially useful when a sentence contains a series of clauses or phrases. For example, try to precede potentially confusing clauses with that, who, when, where, or some other connective, repeating the same connective every time to help readers follow them with ease.
If the same lead-in word won’t work for all elements in a series, try changing the order of the elements to minimize variation.
EXERCISE 18-1 Making Sentences Parallel
Revise the following sentences by substituting parallel structures for awkward ones. Example:
The border separating Texas and Mexico marks not only the political boundary of two countries, but it also is the last frontier for some endangered wildlife.
In the Rio Grande Valley, both local residents and the people who happen to be tourists enjoy visiting the national wildlife refuges.
The tall grasses in this valley are the home of many insects, birds, and there are abundant small mammals.
Two endangered wildcats, the ocelot and another called the jaguarundi, also make the Rio Grande Valley their home.
Many people from Central America are desperate to immigrate to the United States by either legal or by illegal means.
Because the land along the Rio Grande has few human inhabitants and the fact that the river is often shallow, many illegal immigrants attempt to cross the border there.
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To capture illegal immigrants more easily, the U.S. government has cut down tall grasses, put up fences, and the number of immigration patrols has been increased.
For illegal immigrants, crossing the border at night makes more sense than to enter the United States in broad daylight, so the U.S. government has recently installed bright lights along the border.
The ocelot and the jaguarundi need darkness, hiding places, and to have some solitude if they are to survive.
Neither the immigration officials nor have wildlife conservationists been able to find a solution that will protect both the U.S. border and these endangered wildcats.