Modifiers and Parallel Structure — ACT English

Introduction

Dangling modifiers are the ACT's sneakiest trap. The sentence sounds perfectly fine. But when you ask 'who or what is being described by that opening phrase?', the answer is wrong — and the ACT awards full credit only if you catch it.

Modifier and parallel structure questions appear 3–5 times per English section and reward students who can quickly identify what a phrase is modifying and what items in a list are being compared. These are high-ceiling questions — students who master them gain an outsized advantage.

By the end of this lesson you will be able to:

Identify the noun or clause that a modifier is intended to describe and verify that the modifier is adjacent to it
Recognize dangling modifiers where the intended subject of the introductory phrase does not appear as the grammatical subject of the main clause
Apply parallel structure rules to lists, comparisons, and correlative conjunction pairs (not only...but also, either...or, both...and)

'Having studied for three weeks, the exam was finally passed by Maria.' Who studied for three weeks — Maria or the exam? Grammatically, the exam studied. By the end of this lesson, you will fix this in 10 seconds without hesitation.

The Concept

The Core Rule

A modifier must be placed immediately adjacent to the word it modifies. A dangling modifier occurs when the subject of an introductory phrase is not the subject of the main clause. In parallel structure, all items in a list or comparison must use the same grammatical form.

How the ACT tests this

Presents an introductory participial phrase followed by a main clause whose subject is NOT the intended target of the phrase — a dangling modifier
Offers answer choices for a list in which three items are in the same form but one is in a different form (noun vs. gerund, infinitive vs. clause)
Tests correlative conjunction balance: 'not only X but also Y' requires X and Y to be the same grammatical form

Dangling Modifiers — The Core Test

An introductory participial phrase ('Having studied...', 'Born in Vienna...', 'Exhausted by the climb...') must describe the grammatical subject of the clause that immediately follows it. If the subject of the main clause cannot logically perform the action in the phrase, the modifier is dangling.

Dangling: 'Walking through the museum, the paintings were breathtaking.' The paintings were not walking.
Fixed: 'Walking through the museum, we found the paintings breathtaking.' Now 'we' were walking.
Dangling: 'After reviewing the data, the conclusion seemed obvious.' Who reviewed the data? The conclusion did not.
Fixed: 'After reviewing the data, the researchers found the conclusion obvious.'

Misplaced Modifiers

A misplaced modifier is not dangling — the intended noun exists in the sentence but the modifier is placed too far from it, creating an unintended meaning.

Misplaced: 'She only eats vegetables on Tuesdays.' ('Only' modifies 'eats' — she does nothing but eat on Tuesdays?) Better: 'She eats only vegetables on Tuesdays.'
Misplaced: 'The scientist examined the bacteria under the microscope that had mutated.' Did the microscope mutate?
Fixed: 'The scientist examined, under the microscope, the bacteria that had mutated.'

Parallel Structure in Lists

All items in a list must be in the same grammatical form. If item 1 is a noun, items 2 and 3 must be nouns. If item 1 is an infinitive, all items must be infinitives.

Not parallel: 'She enjoys hiking, to swim, and the act of cooking.' (gerund, infinitive, noun phrase)
Parallel: 'She enjoys hiking, swimming, and cooking.' (all gerunds)
Not parallel: 'The project required creativity, that we work hard, and good communication.' (noun, clause, noun)
Parallel: 'The project required creativity, hard work, and good communication.' (all nouns)

Correlative Conjunctions

Correlative conjunctions come in pairs: not only...but also, either...or, neither...nor, both...and, whether...or. The grammatical form of X must match the grammatical form of Y.

Not parallel: 'She is not only a talented writer but also writes with great skill.' (noun phrase vs. verb phrase)
Parallel: 'She is not only a talented writer but also a skilled editor.' (noun phrase...noun phrase)
Not parallel: 'He will either resign or a negotiated settlement will be reached.' (verb phrase vs. clause)
Parallel: 'He will either resign or negotiate a settlement.' (verb...verb)

Your strategy

Step 1 — When you see an introductory phrase ending with a comma, identify what noun or pronoun comes immediately after the comma. Ask: could that subject logically perform the action in the introductory phrase?
Step 2 — If the answer is no, the modifier is dangling. Look for the answer choice that places the correct logical subject immediately after the introductory phrase.
Step 3 — For lists, identify the grammatical form of the first item. Check each subsequent item against that form. Find the answer choice that makes all items match.
Step 4 — For correlative conjunctions, find both halves (not only...but also), identify the grammatical form of the first element, and ensure the second element matches it exactly.

Worked Examples

Easy Example 1 Passive Voice Parallel Trap — Option A Sounds Informative And Complete, But Switching From Active Voice To Passive Voice ('was Documented') Breaks Parallelism With The Other Active-voice List Items.

The research team presented three key findings at the conference: the experiment confirmed the hypothesis, reduced production costs by 12%, [and an improvement in safety outcomes was documented]. Delegates from seven countries attended the session.

Which choice correctly fixes the underlined portion?

A. NO CHANGE
B. and that safety outcomes had improved
C. and improved safety outcomes (Correct answer)
D. and safety outcomes showed improvement

Step 1

Identify the list: the experiment (1) confirmed the hypothesis, (2) reduced production costs, (3) ___.

Step 2

Items 1 and 2 use the structure: [verb] + [object] — 'confirmed the hypothesis,' 'reduced production costs.'

Step 3

Item 3 must follow the same verb + object pattern. 'Improved safety outcomes' uses the past tense verb 'improved' with the object 'safety outcomes' — matching the pattern.

Step 4

Options A, B, and D all shift to noun-led or clause constructions that break the parallel verb + object structure.

Correct answer: C

Why C is correct

Correct — 'improved safety outcomes' mirrors 'confirmed the hypothesis' and 'reduced production costs.'

Why other options are wrong

A: Passive noun phrase ('an improvement...was documented') breaks the active verb + object pattern of the list.

B: 'That safety outcomes had improved' is a subordinate clause — the list already uses verb phrases, not clauses.

D: 'Safety outcomes showed improvement' is a new independent clause that breaks the parallel structure.

⚠ Trap: Passive voice parallel trap — option A sounds informative and complete, but switching from active voice to passive voice ('was documented') breaks parallelism with the other active-voice list items.

Medium Example 2 Passive Voice Dangling Trap — Option B Appears To Fix The Dangling Modifier By Making The Passage's Subject (the Artist) The Focus, But 'her Later Work' Is Still Not What Dominated The Art World.

[Having dominated the art world for over a decade, critics began to question whether her later work had lost its edge.] She responded to the criticism in a lengthy essay published in a prominent arts journal, arguing that evolution was not decline.

Which choice best corrects the underlined portion?

A. NO CHANGE
B. Having dominated the art world for over a decade, her later work was questioned by critics.
C. Having dominated the art world for over a decade, she faced critics who questioned whether her later work had lost its edge. (Correct answer)
D. After she had dominated the art world for over a decade, critics began questioning whether her later work had lost its edge.

Step 1

The introductory phrase 'Having dominated the art world for over a decade' describes someone who dominated the art world.

Step 2

In option A, the subject of the main clause is 'critics' — critics did not dominate the art world. Dangling modifier.

Step 3

In option B, the subject is 'her later work' — her work did not dominate the art world. Still dangling.

Step 4

Option C places 'she' as the subject — she dominated the art world, so the modifier correctly describes 'she.'

Correct answer: C

Why C is correct

Correct — 'she' is the subject and logically could have dominated the art world.

Why other options are wrong

A: 'Critics' is the subject — critics did not dominate the art world. Dangling modifier.

B: 'Her later work' is the subject — the work did not dominate the art world. Still dangling.

D: Grammatically fixes the dangling modifier by restructuring, but removes the participial phrase entirely. While technically correct, option C more elegantly preserves the participial opening that the question is testing.

⚠ Trap: Passive voice dangling trap — option B appears to fix the dangling modifier by making the passage's subject (the artist) the focus, but 'her later work' is still not what dominated the art world.

Hard Example 3 Correlative Conjunction Mismatch Trap — Option C Looks Parallel Because It Makes The List Items (examining, Identifying, Recommending) All Gerunds, But Misses That 'not Only TO Audit' Uses An Infinitive, Making The But-also Half Still Mismatched.

The committee's mandate was not only [to audit existing financial controls] but also examining procurement irregularities, identifying vendor conflicts of interest, and it would recommend systemic reforms to the board.

Which choice best fixes the underlined portion to create parallel structure?

A. NO CHANGE
B. to audit existing financial controls but also to examine procurement irregularities, to identify vendor conflicts of interest, and to recommend (Correct answer)
C. to audit existing financial controls but also examining procurement irregularities, identifying vendor conflicts of interest, and recommending
D. auditing existing financial controls but also examining procurement irregularities, identifying vendor conflicts of interest, and recommending

Step 1

Identify the correlative conjunction: 'not only...but also.' Both halves must be the same grammatical form.

Step 2

In option A, 'not only [to audit]' is an infinitive. 'But also examining...identifying...it would recommend' mixes gerunds and a clause — triple parallelism failure.

Step 3

Option B uses 'not only [to audit] but also [to examine], [to identify], and [to recommend]' — all infinitives throughout. Fully parallel.

Step 4

Option C mixes 'to audit' (infinitive) with 'examining, identifying, recommending' (gerunds) — the 'not only...but also' pair is still mismatched.

Step 5

Option D removes 'to' from 'audit' and uses gerunds throughout, but 'auditing' after 'not only' followed by the correlative structure 'but also' with additional gerunds — grammatically this works, but the sentence now reads awkwardly. Option B is cleaner and fully parallel.

Correct answer: B

Why B is correct

Correct — all four items in the list are infinitives (to audit, to examine, to identify, to recommend).

Why other options are wrong

A: Mixed forms: infinitive + gerunds + clause — not parallel.

C: 'Not only to audit' (infinitive) vs. 'but also examining' (gerund) — the correlative pair itself is mismatched.

D: Gerunds throughout, but 'not only auditing' is grammatically awkward with 'mandate was' — option B reads more naturally and precisely.

⚠ Trap: Correlative conjunction mismatch trap — option C looks parallel because it makes the list items (examining, identifying, recommending) all gerunds, but misses that 'not only TO audit' uses an infinitive, making the but-also half still mismatched.

Strategy Tips

For every introductory participial phrase, circle the first noun after the comma and ask: 'Can this noun logically do what the phrase describes?' If not, it is a dangling modifier.
For lists, identify the form of the first item and write it down (noun, gerund, infinitive, clause). Check every subsequent item against that benchmark.
For 'not only...but also' and other correlative pairs, treat them as a balance beam — both sides must carry the same grammatical weight.
When a modifier is dangling, you usually need to change the subject of the main clause, not just move words around — the answer choice that introduces the correct human subject is almost always right.

Common pitfalls

Passive voice as a false fix: changing 'Walking down the street, the rain began to fall' to 'Walking down the street, the rain was encountered' is still dangling — rain cannot walk.

Adding a pronoun that matches the modifier is not enough: 'Exhausted from the race, it was clear that she needed rest' — 'it' cannot be exhausted. The correct subject must immediately follow the comma.

Lists with 'and' and mixed article use: 'a scientist, an engineer, and teacher' — 'teacher' lacks the article. On the ACT, missing articles can signal a parallelism error in noun lists.

Dangling modifier questions require you to read the full introductory phrase and the full main clause — budget 35–40 seconds. Parallel structure questions can be faster (20–30 seconds) once you identify the form of the first list item.

Summary

An introductory participial phrase must describe the grammatical subject of the clause immediately after the comma — if the subject cannot logically perform the action in the phrase, it is dangling.
All items in a list and both halves of a correlative conjunction pair must be in the same grammatical form — noun, gerund, infinitive, or clause, not a mix.
Passive voice does not fix a dangling modifier — only placing the correct logical subject immediately after the introductory phrase does.

Write 8 sentences: 4 with deliberate dangling modifiers using different participial phrases (having, being, after -ing, while -ing) and 4 with parallel structure violations mixing nouns, gerunds, and clauses. Swap with a partner and fix all 8 in under 5 minutes, writing the rule that applies to each correction.

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