Longer and more complex sentences often require parallel construction. Simply put, parallel construction ensures that any given longer sentence has a standard rhythm or construction. With parallel construction, each pronoun corresponds with another pronoun, each verb corresponds with another verb, each adjective matches with a corresponding adjective and so on. Parallel construction can certainly be found in shorter sentences as well, and to great effect.
Consider the example of Hamlet’s words “To be or not to be,” which are some of the most famous in the English language. Shakespeare wrote this short sentence in perfect parallel form; “to be” is matched perfectly with its corresponding negative “not to be” and is separated only by the necessary word “or.” Another short example of parallel construction from history is “I came, I saw, I conquered.” With these words, Julius Caesar spoke in perfect parallel construction—the grammatical form is a pronoun (the word “I”) followed by a verb in the past tense (“came,” “saw,” “conquered”).
If we were to change that second famous phrase just a touch, the amazing quality it now has would be lost, and the phrase would become unremarkable. For example, if Caesar had said, “I came, I saw, and I became the conqueror,” no one would be quoting him today (because the rhythm would be destroyed—it would be verb, verb, verb phrase). Keep this rule in mind for everything that you write, especially for longer sentences.
Some final examples:
Bad: There are three key reasons for this success: understanding our client, trying harder than our competition and teamwork.
Good: There are three key reasons for this success: understanding our client, trying harder than our competition and working as a team. (In this example, gerunds [the words ending in “ing”] parallel each other, unlike in the previous, “bad” example.)
Bad: We are in the forestry business. We sell wood to hardware stores and paper to stationery stores.
Good: We are in the forestry business. We sell wood and paper.