Errors in parallelism prevent a writer from creating a smooth flow, or coherence, from word to word and sentence to sentence. Writers should create parallel structure in words, phrases, and clauses wherever two or more similar and equally important ideas exist next to each other in a sentence.
Incorrect: Amanda could program computers, repair cars, and knew how to bake croissants.
Correct: Amanda could program computers, repair cars, and bake croissants.
Looking at each part of the list individually helps highlight the error: the final item reads “Amanda could knew how to make croissants.” This error is fixed by writing the verbs in parallel structure: program, repair, and bake.
In sentences with multiple prepositional phrases in a parallel series, the preposition must be repeated unless the same preposition begins each phrase.
Incorrect: You can park your car in the garage, the carport, or on the street.
Correct: You can park your car in the garage, in the carport, or on the street.
In any passage, verb tense should be consistent and make sense in the context of other verbs, adverbs, and general meaning.
Incorrect: Deborah was speaking with her colleague
when her boss will appear, demanding a meeting.
The first part of the sentence states that Deborah was speaking with her colleague, an action occurring in the past. Thus, it would make no sense for her boss to interrupt her in the future (will appear). The sentence can be corrected by putting her boss’s action in the past tense as well.
Correct: Deborah was speaking with her colleague
when her boss appeared, demanding a meeting.
Pay attention to how verbs are conjugated in the beginning of a sentence or passage, and look for adverbial clues to spot any errors in verb tense agreement.