ACT® · English: Sentence Structure and Formation
Parallelism in a Series of Phrases
When a sentence lists three or more phrases, each one has to share the same grammatical pattern, usually signaled by repeating the same preposition or article at the head of every item.
A series only reads as one list if every item is built the same way. 'For the money, for the travel, and because it is fun' breaks because the first two items are prepositional phrases starting with 'for,' and the third is suddenly a clause starting with 'because.' The eye expects the pattern to keep repeating, so the one piece that changes shape is the one that feels wrong, even if you can't name why at first.
The fix is almost always mechanical: pick the pattern the first two items already set, then force the last item into it. 'He trained with weights, with sprints, and by swimming laps' has 'with' twice and then 'by' once. Change the last item to 'with laps in the pool' and all three items are now prepositional phrases headed by 'with.' The repeated word at the front of each phrase is what locks the whole series into place, so check that word first whenever a list feels off.
Two traps hide inside this rule. Repeating 'the' in front of only some items doesn't fix anything, because the problem is the shape of the phrase after the article, not the article itself. And a list can be three phrases in a row and still fail, if one phrase is prepositional, one is a gerund, and one is an adjective doing a different job. Matching part of speech, not just matching 'this is a phrase,' is what the test is actually checking. This sits right next to tense and voice shifts: all of them test whether a sentence holds one consistent pattern from clause to clause.
Key terms
- Parallelism
- Using the same grammatical pattern for each item in a list or comparison.
- Series
- Three or more items joined in one list, usually separated by commas.
- Head word
- The preposition or article placed at the front of a phrase that sets its pattern.
- Prepositional phrase
- A phrase starting with a word like 'for,' 'with,' or 'by' plus its object.
Watch it explained
- How it worksHow does a preposition or article repeated at the head of each phrase lock the pattern into place?
- Worked exampleWalk me through fixing 'He trained with weights, with sprints, and by swimming laps' into one pattern.
- Common mistakeWhy doesn't repeating a word like 'the' in front of only some items in a list count as parallel?
- Common mistakeWhy isn't a list parallel merely because every item happens to be a phrase rather than a clause?
Check yourself
End of topic.