Parallel Sentences
Have you ever been on a flight when an attendant asked you to move your seat to help balance the aircraft? If the attendants didn't do this, the plane would probably still fly, but you'd be in for a rough flight.
- sentence without parallel structure is like an imbalanced aircraft; it'll get you from point A to point
- but no one's going to congratulate the pilot when it lands.
Coordinating Conjunctions
To spot potential parallelism pitfalls, first look for the coordinating conjunctions in a sentence those are for, and,nor, but, or, yet, and so - and then look to either side of the conjunction to see if it's parallel. So here's an example of a sentence without parallel structure:
Deep-fried Oreos are delicious but bad nutrition.
So we have 'delicious' on one side and 'nutrition' on the other of the coordinating conjunction, but the former is an adjective and the latter is a noun. Here's the same sentence with parallel structure:
Deep-fried oreos are delicious but not nutritious.
Now both of the descriptors are adjectives and the sentence is balanced.
Parallel structure is about style. It's about the way that a sentence feels and flows. Yes, it's part of grammar, but it's also part of what makes an essay or a sentence sound good to the reader's ear.
Correlative Conjunctions
Sentences that contain correlative conjunctions must also be parallel. So a correlative conjunction can take the form of either...or, neither...nor, both ... and, and not only ... but also. These pairings highlight a connection, or correlation, between two elements. Here's an example of a sentence that uses correlative conjunctions but is not parallel:
We not only were lost but also broke.
Now the correlative conjunction here is not only ... but also, and if you stick the verb were in the middle of it, it breaks it up and makes it not parallel. So there are two different ways you can balance this sentence.
You could do we not only were lost, but also were broke. You have two verbs and those are on either side of the coordinating conjunction, which is but, or you could stick the verb before the correlative conjunction: we were not only lost, but also broke.
The structures directly following the conjunctions have to match and that's the important lesson about parallel structure.
Items in a Series
One of the most common parallel structure mistakes occurs when writers list items in a series. You're bounding over the hills and dales of a sentence when suddenly, just before you reach your destination, the car hits a ditch. Here's an example:
Sasquatch enjoys taking long walks in the forest, playing with small woodland creatures, and to devour wandering tourists.
Now, instead of all ing words called gerunds in the series, the sentence hits a hitch at the infinitive to devour.Matching the verb-forms restores the balance, so it should be:
Sasquatch enjoys taking long walks in the forest, playing with small woodland creatures, and devouring wandering tourists.