Five Parallelism Problems in Sentence Structure

It’s easy to produce a faultily constructed sentence by neglecting to install all the necessary parts. Each of the sentences below lacks a small but essential component that helps render the statement sturdy and structurally sound; read each discussion for an explanation of the flaw.

1. ‘Lifelong interest and enthusiasm for science is instilled through science literacy.’
Take the phrase ‘and enthusiasm’ out of the sentence, and you’re left with ‘Lifelong interest for science is instilled through science literacy.’ Here, the subject is followed by the wrong preposition. Omit ‘and enthusiasm for,’ and the result is ‘Lifelong interest science is instilled through science literacy.’ Now, the subject lacks any preposition. The solution? Each noun in the noun phrase ‘interest and enthusiasm’ requires its own appropriate preposition: ‘Lifelong interest in and enthusiasm for science is instilled through science literacy.’ (Depending on emphasis desired, ‘and enthusiasm for’ may be bracketed by a pair of commas, parentheses, or em-dashes but is correct without any interruptive signals.)

2. ‘They’re noisy, they’re tiny, weigh fifty pounds, and can be souped up from a speed of thirty-five miles per hour.’
Of the four elements in this list, two are preceded by pronouns and two aren’t. To achieve parallel compliance, all the elements must share one pronoun (‘They’re noisy, tiny, weigh fifty pounds, and can be souped up from a speed of thirty-five miles per hour’), or each requires its own (‘They’re noisy, they’re tiny, they weigh fifty pounds, and they can be souped up from a speed of thirty-five miles per hour’).

3. ‘They run farther, longer, and never get fat.’
The first two elements share a verb, and the third has its own. However, just as in the apportionment of pronouns in the example above, one verb must apply to all, or each element must have its own verb (especially if a single verb is not appropriate for all the elements).

In this case, the verbs must differ. Depending on the context, either revise the sentence so that farther and longer share the verb run (‘They run farther and longer and never get fat’), or provide longer with its own verb (‘They run farther, last longer, and never get fat’).

4. ‘John Smith is off the streets, sober, and has a job.’
The rule set forth in the previous sentence applies for simple ‘to-be’ verbs as well. Revise the sentence to read, ‘John Smith is off the streets, is sober, and has a job’ or ‘John Smith is off the streets and sober and has a job.’

5. ‘That opinion was uttered not by John Doe, but one of his vice presidents.’
The preposition by must be repeated at the head of the second clause to match the structure of the first clause: ‘That opinion was uttered not by John Doe, but by one of his vice presidents.’ The sentence could be recast in active voice (‘One of John Doe’s vice presidents, not Doe himself, uttered that opinion’), but the change doesn’t necessarily improve the statement.