One aspect of writing that even native English speakers sometimes overlook is parallelism. This refers to using a consistent grammatical construction throughout a sentence. Faulty parallelism, meanwhile, occurs when different parts of a sentence use different grammatical structures.
If you want to ensure that your written work is easy to read, then, you should look out for the following types of parallelism.
1. Verb Tense
One of the most prominent errors made in terms of parallelism is mixing verb tenses in a sentence, such as in the following:
Incorrect: Marc picks up the hammer and hit the nail.
Here, the simple present tense verb ‘picks’ is used in the same sentence as the simple past tense verb ‘hit’. To ensure a parallel construction, a single verb tense should be used throughout:
Present tense: Marc picks up the hammer and hits the nail.
Past tense: Marc picked up the hammer and hit the nail.
Both sentences above are grammatically correct, so you could use either. It’s just a matter of which tense works in context.
2. Infinitives and Gerunds
Another common error is mixing infinitive verbs (i.e. to + verb) and gerunds (i.e. verbs ending in ‘-ing’ used as a noun) in a single sentence:
Incorrect: Marc likes to make and repairing furniture.
This is wrong because ‘to make’ is an infinitive verb form, while ‘repairing’ is a gerund. To correct this, we’d have to rephrase the sentence using one form:
Infinitives: Marc likes to make and to repair furniture.
Gerunds: Marc likes making and repairing furniture.
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It can be easy to miss faulty parallelism like this in lists with multiple items, so make sure to check carefully.
3. Nouns, Adverbs and Adjectives
It’s also a good idea not to mix nouns, adverbs and adjectives in descriptive sentences. For example, while we could say:
Incorrect: When Marc makes a mistake, he feels frustration and angry.
However, this combines a noun (‘frustration’) with an adjective (‘angry’). Ideally, we would rewrite this sentence to use one form in both cases:
Nouns: When Marc makes a mistake, he feels frustration and anger.
Adjectives: When Marc makes a mistake, he feels frustrated and angry.
Both of these are correct, since each sentence uses a parallel construction.
4. Plural and Singular Nouns
Parallelism also suggests that you shouldn’t mix plural and singular nouns, especially when giving examples. For instance:
Incorrect: DIY requires tools, such as a hammer, drills and screwdrivers.
Here, for instance, the singular ‘hammer’ is combined with the plurals ‘drills’ and ‘screwdrivers’. But it would be better to use the same form for all:
Correct: DIY requires tools, such as hammers, drills and screwdrivers.
Note, though, that this isn’t the case when one of the nouns listed is an uncountable noun, which can be used alongside plural nouns even though they are typically treated as singular.