5 Parallel Structure Rules for TOEFL ITP: And/But/Or, Correlatives, Comparisons, and The More
Parallel structure in TOEFL ITP: 5 rules for and/but/or, correlatives, comparisons, and the more, in Structure and Written Expression, with a quiz.
“He loves swimming, jogging, and to cycle.” The meaning is clear, yet a TOEFL® examiner would mark it wrong.
The problem is parallel structure. The principle is simple: if the first item uses form A, every item joined with it must use form A too. Swimming and jogging are gerunds (-ing), so the third item has to be cycling.
In TOEFL ITP Structure & Written Expression, especially the Written Expression part (25 find-the-error questions), faulty parallelism is one of the most common errors. Here are the 5 rules. (The slides below are in Indonesian, with the English examples.)
Why Parallel Structure Matters on TOEFL
Parallelism questions are “cheap” to write: the test writer just changes one item in a series into a different word class. The sentence is still understandable, so many test takers skip right past it.
The trick: every time you see and, but, or, a pair like both…and, or comparison words like than and as…as, pause and check both sides. If the forms differ, that’s your likely answer.
Rule 1: Parallelism with AND, BUT, OR
The items before and after a coordinate conjunction must be the same word class: noun with noun, adjective with adjective, verb with verb, phrase with phrase.
✅ The new software is efficient, reliable, and economical. (adjective, adjective, adjective) ❌ The new software is efficient, reliable, and it saves money. (adjective, adjective, clause)
✅ She enjoys reading novels and writing poems. ❌ She enjoys reading novels and to write poems.
If word classes still trip you up, start with Parts of Speech 101.
Rule 2: Correlative Conjunctions Must Match
These four pairs must be followed by exactly the same form on both sides:
- both … and …
- either … or …
- neither … nor …
- not only … but also …
✅ The grant covers not only tuition but also books. (noun & noun) ❌ The grant covers not only tuition but also providing books. (noun & gerund)
✅ You can pay either by card or by bank transfer. ❌ You can pay either by card or you can transfer the money.
There are two traps here. First, the forms after each half aren’t parallel. Second, the pair itself is broken, for example neither…or (should be neither…nor) or both…or (should be both…and).
Rule 3: Parallelism in Comparisons
The things compared must be logically equivalent: climate with climate, price with price, not climate with a city.
❌ The climate of Bali is warmer than Jakarta. ✅ The climate of Bali is warmer than that of Jakarta. ✅ The climate of Bali is warmer than the climate of Jakarta.
The first sentence compares Bali’s climate with the city of Jakarta, which is illogical. To avoid repeating the noun, use that of for a singular noun and those of for a plural noun.
✅ The prices in this store are lower than those of the mall.
When the subject has the shape the [noun] of … (the climate of, the cost of, the population of), be suspicious of whatever follows than.
Rule 4: Series of Verbs and Gerunds Must Stay Uniform
In a series of three or more actions, the verb form must not switch halfway. If it starts with -ing, keep -ing to the end. If it starts with to + base verb, keep that too.
“The committee focuses on researching clean energy, developing new technology, and _____.”
(A) to promote green policy (B) promoting green policy (C) promotion of green policy (D) they promote policy
Answer: (B)
Researching and developing are both gerunds, so the third item must be promoting. Option (A) switches to an infinitive, (C) becomes a noun phrase, and (D) starts a new clause.
Rule 5: The Double Comparative “The More…, The More…”
The “the more…, the more…” pattern must start with the + comparative in both clauses.
Formula: The + comparative + S + V, the + comparative + S + V
✅ The older we grow, the wiser we become. ✅ The more you practice, the better results you achieve. ❌ The more you practice, you will get better results.
The wrong sentence opens with The more but turns the second half into an ordinary clause. Quick strategy: if the sentence starts with The more or The + -er, look for an option after the comma that also starts with the + comparative.
The 5 Rules at a Glance
| Rule | Pattern | Correct example |
|---|---|---|
| And, but, or | X + and + X (same word class) | efficient, reliable, and economical |
| Correlatives | both X and X, not only X but also X | not only tuition but also books |
| Comparisons | the N of A … than that/those of B | warmer than that of Jakarta |
| Verb series | -ing, -ing, and -ing | researching, developing, and promoting |
| Double comparative | The + comp …, the + comp … | The more you practice, the better you get |
Quick Quiz
Find the part that isn’t parallel:
- The job requires patience, creativity, and being able to work in a team.
- She is not only smart but also works hard.
- The population of Tokyo is larger than London.
Answers:
- Replace with teamwork (a noun, parallel with patience and creativity).
- Replace with but also hardworking (an adjective, parallel with smart).
- Replace with that of London (population compared with population).
Practice Parallel Structure for Real
A trained eye can spot a parallelism error in a few seconds. The key is practicing Written Expression questions until “check both sides” becomes a habit.
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