ACT Conventions of Standard English: Grammar and Usage

Last updated: May 2, 2026

Conventions of Standard English: Grammar and Usage questions are one of the highest-leverage areas to study for the ACT. This guide breaks down the rule, the elements you need to recognize, the named traps that catch most students, and a memory aid that scales to test day. Read it once, then practice the same sub-topic adaptively in the app.

The rule

Grammar and usage items test whether the words on the page actually fit together — whether subjects match verbs in number, pronouns match what they refer to, modifiers sit beside what they modify, and items in a series share the same grammatical form. The ACT is not asking what sounds nicest; it is asking what is mechanically correct. For every underlined portion, identify which of these four relationships is being tested and verify the relationship before you choose.

Elements breakdown

Subject-verb agreement

A verb must match its true grammatical subject in number, regardless of any words that sit between them.

  • Locate the head noun of the subject
  • Cross out prepositional phrases that follow it
  • Decide singular or plural
  • Match the verb's number to the head noun
  • Watch for inverted order (Here/There is/are…)

Common examples:

  • The box [of old letters] was on the shelf.
  • There are three reasons we delayed.

Pronoun-antecedent agreement and case

A pronoun must agree in number and gender with the noun it stands in for, and its case must fit its job in the clause.

  • Find the antecedent the pronoun refers to
  • Match number (singular/plural) and gender
  • Check case: subject (he/she/they), object (him/her/them), possessive (his/her/their)
  • Treat each, every, anyone, neither, either as singular
  • Distinguish who (subject) from whom (object)

Verb tense and sequence

Verb tenses should stay consistent within a passage unless the writing signals a real shift in time.

  • Scan tense of nearby verbs
  • Look for time-shift signals (yesterday, by then, since, will)
  • Maintain past series with simple past; perfect tense only for prior action
  • Avoid drifting between past and present narration

Modifier placement

Modifying phrases must sit next to the noun or verb they describe; otherwise the sentence misattaches the description.

  • Identify the modifying phrase
  • Ask what the phrase logically describes
  • Place the modifier directly beside that noun
  • For introductory phrases, the noun must follow the comma
  • Reject any reading that produces a physical or logical absurdity

Parallel structure

Items joined by and, or, or correlative conjunctions (both…and, not only…but also) must share the same grammatical form.

  • Find the connecting word (and/or/but)
  • List the items in the series
  • Confirm each is the same form: verb, noun, gerund, or infinitive
  • Match correlative pairs (not only X but also Y) on both sides

Common patterns and traps

The Intervening-Phrase Trap

The subject of the sentence is followed by a prepositional phrase whose object is the opposite number from the subject. The verb is supposed to agree with the head noun, but the closer noun in the prepositional phrase is what your ear hears, so the wrong-number verb sounds correct. This is the single most common subject-verb item on the test.

A choice keeps a plural verb after a singular head noun (or vice versa) because a prepositional phrase containing the opposite-number noun sits between subject and verb.

The Indefinite-Pronoun Trap

Indefinite pronouns like each, every, anyone, either, neither, and none are grammatically singular even when followed by a plural prepositional phrase. The test sets these up with a plural noun nearby, then offers a plural pronoun or verb that matches the wrong word. The fix is to anchor agreement on the indefinite pronoun, not the noun beside it.

A choice pairs a plural pronoun (their, them) or plural verb (have, are) with a sentence whose actual subject is each, every, or neither.

The Tense-Drift Trap

A passage establishes a clear tense — usually simple past for narration — and the underlined verb shifts into present, present perfect, or progressive without a time-shift signal in the surrounding sentences. Because the underlined verb still describes a real action, students often miss that the tense itself is the error. Always read the verbs immediately before and after the underlined portion.

A choice substitutes is/has/will for the past-tense verb the rest of the paragraph uses, with no 'today,' 'now,' or 'by then' to justify the change.

The Dangling-Modifier Trap

An introductory phrase describes an action, and the noun that follows the comma is not the thing performing that action. The sentence then literally claims something impossible — a wasp's nest spotting children, a soup recipe baking a cake. The fix is to make sure the subject of the main clause is whatever the introductory phrase logically modifies.

A choice keeps an introductory -ing or -ed phrase but follows it with a subject that cannot perform the introductory action.

The Faulty-Parallelism Trap

A series joined by and or or contains items in mismatched grammatical forms — a clause where there should be an infinitive, a gerund where there should be a bare verb, a noun phrase where there should be a verb phrase. The wrong choice usually keeps the meaning intact but breaks the form. Rewrite the series in your head, item by item, and confirm they share the same shape.

A choice in a three-item series uses 'that they should X' or 'X-ing' while the other two items are bare infinitives sharing a single 'to.'

How it works

Suppose you read, 'The basket of ripe peaches were sitting on the counter.' Your ear may not flinch, but the subject is 'basket' — singular — not 'peaches.' Strip away the prepositional phrase 'of ripe peaches' and the sentence reads 'The basket were sitting,' which is plainly wrong. Swap 'were' for 'was' and the agreement repairs itself. The ACT almost always slips a phrase or two between subject and verb precisely to mislead your ear. The same diagnostic move works for every grammar item: name the relationship being tested (subject-verb, pronoun-antecedent, modifier-noun, parallel-series), strip away the noise, and check whether the underlined word fits the structural job, not whether it merely sounds smooth.

Worked examples

Worked Example 1
The collection of antique brass instruments displayed in the museum's east wing [were polished] to a mirror shine every Friday by the conservator on staff.

Which choice best replaces the bracketed portion?

  • A NO CHANGE
  • B was polished ✓ Correct
  • C were being polished
  • D polished

Why B is correct: The grammatical subject is 'collection,' which is singular; 'of antique brass instruments displayed in the museum's east wing' is a prepositional phrase plus participial modifier sitting between subject and verb. Strip those out and the sentence reads 'The collection ___ polished... by the conservator,' which requires the singular passive 'was polished.'

Why each wrong choice fails:

  • A: The plural 'were' disagrees with the singular subject 'collection.' Your ear hears the nearby plural 'instruments,' but that noun is locked inside a prepositional phrase and cannot govern the verb. (The Intervening-Phrase Trap)
  • C: Still plural 'were' — same agreement error, just dressed up in progressive aspect. The aspect change does not address the underlying singular-subject problem. (The Intervening-Phrase Trap)
  • D: Dropping the auxiliary turns 'polished' into an active past-tense verb, which makes the collection the agent doing the polishing — but the trailing 'by the conservator on staff' phrase only makes sense if the verb is passive. The sentence collapses in meaning.
Worked Example 2
Each of the senior physicists who reviewed the manuscript before publication submitted [their] comments to the editor by the end of March.

Which choice best replaces the bracketed word?

  • A NO CHANGE
  • B his or her ✓ Correct
  • C his or hers
  • D there

Why B is correct: The antecedent is 'Each,' which is singular even when followed by a plural prepositional phrase ('of the senior physicists'). Standard written English requires a singular pronoun, and the slot before the noun 'comments' calls for the determiner form 'his or her.'

Why each wrong choice fails:

  • A: The plural pronoun 'their' disagrees in number with the singular antecedent 'Each.' The plural 'physicists' is locked inside a prepositional phrase and cannot serve as the antecedent. (The Indefinite-Pronoun Trap)
  • C: 'His or hers' is the predicate possessive form (used without a following noun, as in 'the comments are hers'). The slot here is followed by the noun 'comments' and requires the determiner form, not the predicate form.
  • D: 'There' is an entirely different word — an existential expletive or a location adverb — and is not a possessive at all. The choice exploits the homophone 'there/their.'
Worked Example 3
The orientation packet advises new hires to arrive early, dress professionally, and [that they should bring] two forms of identification on the first day.

Which choice best replaces the bracketed portion?

  • A NO CHANGE
  • B bring ✓ Correct
  • C bringing
  • D to bring

Why B is correct: The series is governed by a single shared 'to': the packet advises new hires 'to [arrive] early, [dress] professionally, and [bring]…' Each item should be a bare infinitive that the leading 'to' can carry across all three slots. Only 'bring' produces clean parallel form.

Why each wrong choice fails:

  • A: Shifts from a bare infinitive to a subordinate clause ('that they should bring'), which breaks the three-item parallel structure mid-series. (The Faulty-Parallelism Trap)
  • C: The gerund 'bringing' is a different grammatical form from the bare infinitives 'arrive' and 'dress' earlier in the series. Mixing -ing forms with infinitives breaks parallelism. (The Faulty-Parallelism Trap)
  • D: Repeats 'to' even though the series already shares one — producing 'to arrive early, dress professionally, and to bring,' which is asymmetrical. The shared 'to' must apply to all items or to none. (The Faulty-Parallelism Trap)

Memory aid

SPMP — Subject-verb, Pronoun-antecedent, Modifier-noun, Parallel-series. On every grammar item, name which of the four is being tested before you pick. Most wrong answers fail because students treat the question generically and choose by ear.

Key distinction

Grammar and usage tests structural relationships, not style or sound. Two choices can both sound smooth; only one keeps the structural relationship — subject-verb number, pronoun-antecedent reference, modifier adjacency, or parallel form — intact. Identify the relationship first, then choose.

Summary

Don't trust your ear — name the relationship being tested (SPMP), strip out the noise, and confirm the underlined word actually fits.

Practice conventions of standard english: grammar and usage adaptively

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Frequently asked questions

What is conventions of standard english: grammar and usage on the ACT?

Grammar and usage items test whether the words on the page actually fit together — whether subjects match verbs in number, pronouns match what they refer to, modifiers sit beside what they modify, and items in a series share the same grammatical form. The ACT is not asking what sounds nicest; it is asking what is mechanically correct. For every underlined portion, identify which of these four relationships is being tested and verify the relationship before you choose.

How do I practice conventions of standard english: grammar and usage questions?

The fastest way to improve on conventions of standard english: grammar and usage is targeted, adaptive practice — working questions that focus on your specific weak spots within this sub-topic, getting immediate feedback, and revisiting items you missed on a spaced-repetition schedule. Neureto's adaptive engine does this automatically across the ACT; start a free 7-day trial to see your sub-topic mastery climb in real time.

What's the most important distinction to remember for conventions of standard english: grammar and usage?

Grammar and usage tests structural relationships, not style or sound. Two choices can both sound smooth; only one keeps the structural relationship — subject-verb number, pronoun-antecedent reference, modifier adjacency, or parallel form — intact. Identify the relationship first, then choose.

Is there a memory aid for conventions of standard english: grammar and usage questions?

SPMP — Subject-verb, Pronoun-antecedent, Modifier-noun, Parallel-series. On every grammar item, name which of the four is being tested before you pick. Most wrong answers fail because students treat the question generically and choose by ear.

What is "The intervening-phrase trap" in conventions of standard english: grammar and usage questions?

matching the verb to the nearest noun instead of the real subject.

What is "The sounds-fine trap" in conventions of standard english: grammar and usage questions?

trusting your ear over the grammatical relationship being tested.

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