MASTER SERIES
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ACT English · Master Series

Core Concepts
& Key Rules

Review the essential grammar, punctuation, and rhetoric rules before tackling the 20 exam-style questions below.

20
Questions
5
Units Covered
40
Minutes

📖 Concept Review & Key Rules

Unit 1 · Grammar
Subject-Verb Agreement & Verb Tense
The verb must agree with its subject in number and person. Intervening phrases do not change the subject. Verb tense must be consistent with the timeline of events.
⚡ Must Memorize
  • Singular subjects → singular verb: Each student has
  • Collective nouns (team, group) → usually singular
  • Neither/nor → verb agrees with nearest subject
  • Past perfect = had + V-ed (action before another past action)
❌ The team of players are exhausted.
✅ The team of players is exhausted.
Unit 2 · Grammar
Pronoun Agreement & Case
Pronouns must agree with their antecedents in number and gender. Use subject pronouns (I, he, she, they) for subjects; object pronouns (me, him, her, them) for objects.
⚡ Must Memorize
  • Indefinite pronouns (everyone, each) → singular: he or she
  • Who = subject; Whom = object
  • Its = possessive; It's = it is
  • Avoid ambiguous pronoun reference
❌ Everyone must bring their own lunch. (formal/traditional)
✅ Everyone must bring his or her own lunch.
Unit 3 · Punctuation
Commas, Semicolons & Colons
Commas join independent clauses with FANBOYS. Semicolons separate two independent clauses. Colons introduce lists or explanations after a complete sentence.
⚡ Must Memorize
  • FANBOYS: For, And, Nor, But, Or, Yet, So
  • Semicolon = two complete sentences joined
  • Colon: what follows must be a list or explanation
  • No comma between compound predicates
❌ She studied hard, however she failed.
✅ She studied hard; however, she failed.
Unit 3 · Punctuation
Apostrophes & Possessives
Apostrophes show possession or indicate contractions. Plural possessives take an apostrophe after the s. Never use an apostrophe to form plurals.
⚡ Must Memorize
  • Singular possessive: dog's, James's
  • Plural possessive: dogs', the Joneses'
  • its (possessive) vs. it's (it is)
  • their / there / they're — never interchangeable
❌ The student's books are overdue (ambiguous).
✅ The students' books are overdue. (plural)
Unit 4 · Style
Modifiers & Parallel Structure
Modifiers must be placed directly next to the word they modify. Dangling modifiers occur when there is no clear subject to modify. Parallel structure requires consistent grammatical form in lists.
⚡ Must Memorize
  • Dangling modifier fix: rewrite so the subject matches
  • Parallel: noun, noun, noun — NOT noun, verb, adjective
  • Correlatives: both...and, either...or, not only...but also
❌ Running to the bus, the rain began to fall.
✅ Running to the bus, she felt the rain begin to fall.
Unit 5 · Rhetoric
Organization, Transitions & Conciseness
Good writing uses appropriate transition words to signal relationships between ideas. Eliminate redundancy and wordiness. Sentences must serve the purpose of the paragraph.
⚡ Must Memorize
  • Addition: furthermore, moreover, in addition
  • Contrast: however, nevertheless, on the other hand
  • Cause/Effect: therefore, consequently, as a result
  • Redundancy = automatic wrong answer on ACT
❌ She is a female woman who leads the team.
✅ She is a woman who leads the team.
✏️

ACT English — 20 Exam-Style Questions

Read each passage excerpt carefully. Write your corrected answer in the box, then click Submit. Immediate feedback is provided after each question.

01
Unit 1 · Subject-Verb Agreement
Error Correction — Underlined Word/Phrase
Easy
The collection of rare manuscripts were donated to the university library last spring.
The underlined verb is grammatically incorrect. Write the correct form of the verb.
02
Unit 1 · Verb Tense
Error Correction — Underlined Word/Phrase
Medium
By the time the rescue team arrived, the hikers waited in the cave for nearly six hours.
The underlined verb does not reflect the correct time sequence. Write the correct verb form.
03
Unit 2 · Pronoun Case
Error Correction — Underlined Word/Phrase
Medium
The award was given to both my colleague and I for outstanding performance.
The underlined pronoun is in the wrong case. Write the correct pronoun.
04
Unit 2 · Who vs. Whom
Error Correction — Underlined Word/Phrase
Hard
The professor, who the dean selected for the award, will present her research next Friday.
Identify whether the underlined relative pronoun is correct or incorrect. If incorrect, write the correct word.
05
Unit 3 · Comma Splice
Sentence Revision
Medium
The storm knocked out the power, the residents lit candles throughout the night.
The sentence contains a comma splice. Rewrite the underlined portion to fix the error. (Do not change the meaning.)
06
Unit 3 · Semicolon vs. Colon
Error Correction — Punctuation
Hard
The exhibit features works by three artists; Kahlo, Basquiat, and Warhol.
The punctuation mark used is incorrect. Write only the correct punctuation mark that should replace the semicolon.
07
Unit 3 · Apostrophe / Possessive
Error Correction — Underlined Word
Easy
The scientists presented there findings at the annual conference in Geneva.
The underlined word is used incorrectly. Write the correct word.
08
Unit 3 · Apostrophe — Possessive
Error Correction — Underlined Word/Phrase
Medium
The two countries' leaders signed the agreement after months of negotiation.
Is the apostrophe used correctly in the underlined phrase? Write "correct" if it is, or write the corrected version if it is not.
09
Unit 4 · Dangling Modifier
Sentence Revision
Hard
Having finished the exam early, the remaining time was used to review her answers.
The sentence contains a dangling modifier. Rewrite the sentence so the modifier correctly modifies its intended subject. (Keep the same meaning.)
10
Unit 4 · Parallel Structure
Error Correction — Underlined Phrase
Medium
The new employee was praised for her punctuality, being creative, and her professionalism.
The underlined phrase breaks parallel structure. Rewrite the underlined phrase in its correct parallel form.
11
Unit 5 · Redundancy
Conciseness — Identify the Redundant Phrase
Easy
The autopsy revealed the true cause of death: the victim had died from a fatal and deadly poison.
Identify and write the redundant word(s) in the underlined passage that should be removed.
12
Unit 5 · Transitions
Transition Word Selection
Medium
The research team tested the hypothesis three times. [BLANK], the results were inconsistent each time.
Choose the most appropriate transition word or phrase to fill in [BLANK] and write it below. (The second sentence presents a surprising, contrasting outcome.)
13
Unit 1 · Neither/Nor Agreement
Error Correction — Underlined Verb
Hard
Neither the manager nor the employees was informed about the sudden policy change.
Is the underlined verb correct? Write "correct" if it is, or write the corrected verb if it is not.
14
Unit 4 · Misplaced Modifier
Sentence Revision
Hard
Covered in chocolate, the children eagerly ate the strawberries.
The underlined sentence contains a misplaced modifier. Rewrite it so the modifier clearly refers to the intended noun.
15
Unit 2 · Pronoun Ambiguity
Sentence Revision
Medium
After Maria spoke with Elena, she decided to resign from her position.
The pronoun "she" is ambiguous. Rewrite the sentence to make clear that Maria (not Elena) decided to resign.
16
Unit 5 · Sentence Organization
Rhetoric — Sentence Relevance
Hard
The Amazon rainforest is often called the "lungs of the Earth" because it produces vast amounts of oxygen. Deforestation threatens this vital ecosystem. Brazil is the largest country in South America by total area. Protecting the rainforest is therefore critical to global climate stability.
The underlined sentence disrupts the paragraph's focus. Should it be kept or deleted? Write "delete" and explain in one sentence why it should be removed.
17
Unit 3 · Comma Usage
Error Correction — Punctuation
Medium
My brother who lives in Seattle, is visiting us next weekend.
There is a punctuation error in this sentence. Rewrite the sentence with the correct punctuation. (Consider whether the clause is restrictive or non-restrictive.)
18
Unit 4 · Correlative Conjunctions
Error Correction — Underlined Phrase
Hard
The committee will either approve the proposal or it will reject it by the end of the month.
The underlined construction violates parallel structure with the correlative conjunction "either...or." Rewrite only the underlined portion in correct parallel form.
19
Unit 5 · Wordiness / Conciseness
Conciseness — Rewrite Concisely
Medium
Due to the fact that the bridge was under construction, the commuters were forced to take an alternate route.
The underlined phrase is unnecessarily wordy. Replace it with a single, more concise word that carries the same meaning.
20
Unit 1–5 · Comprehensive
Full Passage Correction — All Units
Hard
[Error-Embedded Passage]

Last year, a group of researchers (A) have discovered a new species of deep-sea fish near the Mariana Trench. The team, which consisted of marine biologists and oceanographers, (B) were astonished by the creature's bioluminescent patterns. (C) Swimming at depths exceeding 8,000 meters, the scientists documented the fish using high-resolution cameras. (D) Furthermore, the fish appeared to be completely blind — an adaptation common in deep-sea environments.
Errors are marked (A), (B), (C), and (D). Identify which labels contain errors and write the corrected version for EACH error you find. Write "correct" for any that are already acceptable.
FINAL SCORE
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📋 Full Answer Key & Explanations