Grammar & Usage
Agreement, pronouns, verb tense, sentence structure, modifiers and commonly confused words.
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Grammar & Usage
Agreement, pronouns, verb tense, sentence structure, modifiers and commonly confused words.
📝 Subject-Verb Agreement
Part 1 of 7 — Tricky Subjects, Prepositional Phrases & Compound Subjects
The ACT English section frequently tests whether you can match a subject to its verb in number (singular or plural). The trick is that the ACT hides the true subject behind extra words.
The Core Rule: A singular subject takes a singular verb; a plural subject takes a plural verb.
| Subject | Verb | Example |
|---|---|---|
| Singular | Singular | The dog runs in the yard. |
| Plural | Plural | The dogs run in the yard. |
Why it matters on the ACT: Subject-verb agreement shows up regularly in the Conventions of Standard English questions on the 50-question English test, which makes it one of the highest-yield grammar topics you can study.
🗣️ Pronoun Usage
Part 2 of 7 — Agreement, Case, Ambiguous Reference & Who/Whom
Pronoun questions are a staple of ACT English. The test checks three things:
- Agreement — Does the pronoun match its antecedent in number?
- Case — Is the pronoun in the right form (subject vs. object)?
- Clarity — Is it clear what the pronoun refers to?
| Pronoun Type | Subject | Object | Possessive |
|---|---|---|---|
| First person singular | I | me | my / mine |
| Third person singular | he / she | him / her | his / her |
| Third person plural | they | them | their |
| Relative | who | whom | whose |
⏳ Verb Tense Consistency
Part 3 of 7 — Tense Shifts, Perfect Tenses & Sequence of Events
The ACT tests whether you can keep verb tenses consistent within a sentence and across a passage. Unnecessary tense shifts are one of the most common errors tested.
| Tense | Example | When to Use |
|---|---|---|
| Simple present | She walks | Habitual actions, general truths |
| Simple past | She walked | Completed past actions |
| Present perfect | She has walked | Past action with present relevance |
| Past perfect | She had walked | Action completed before another past action |
| Future | She will walk | Actions that haven't happened yet |
The Golden Rule: Don't shift tenses unless there's a reason (a time change, a shift from general truth to specific event, etc.).
🔗 Sentence Structure
Part 4 of 7 — Fragments, Run-Ons, Comma Splices & How to Fix Them
The ACT tests your ability to recognize and fix sentence-structure errors. These fall into three categories:
| Error | Definition | Example |
|---|---|---|
| Fragment | Missing a subject, verb, or complete thought | Because the rain started. |
| Run-on | Two independent clauses joined with no punctuation | I studied hard I passed the test. |
| Comma splice | Two independent clauses joined with only a comma | I studied hard, I passed the test. |
(Some books call both of the last two errors "run-ons." This lesson uses "run-on" for the no-punctuation version and "comma splice" for the comma-only version. The fixes are the same.)
ACT Tip: If an answer choice creates a fragment or a run-on, eliminate it — the ACT never rewards incomplete or improperly joined sentences.
✨ Modifiers & Parallelism
Part 5 of 7 — Dangling Modifiers, Misplaced Modifiers & Parallel Structure
The ACT tests your ability to place modifiers correctly and keep sentence elements parallel. These errors can be subtle, so learning the patterns is essential.
Key Concepts:
| Error | What Happens | Example |
|---|---|---|
| Dangling modifier | The modifier has no logical subject | Walking to class, the bell rang. |
| Misplaced modifier | The modifier is next to the wrong word | She almost drove her kids to every game. |
| Faulty parallelism | List items don't have the same form | She likes running, swimming, and to hike. |
🔤 Commonly Confused Words
Part 6 of 7 — Affect/Effect, Their/There/They're, Its/It's & More
The ACT includes several questions that test whether you know the difference between commonly confused words. These are easy points once you learn the pairs.
| Pair | Rule |
|---|---|
| affect / effect | Affect = verb (to influence); Effect = noun (the result) |
| their / there / they're | Their = possessive; There = place; They're = they are |
| its / it's | Its = possessive; It's = it is / it has |
| your / you're | Your = possessive; You're = you are |
| then / than | Then = time; Than = comparison |
| who's / whose | Who's = who is; Whose = possessive |
| to / too / two | To = preposition/infinitive; Too = also/excessively; Two = 2 |
🏆 Review & Mixed Practice
Part 7 of 7 — Error-Identification Cheat Sheet & Mixed ACT English Questions
This final lesson brings together everything from Parts 1–6. Use the cheat sheet below for quick reference, then tackle the mixed practice questions.
Grammar Error Cheat Sheet
| Category | What to Check |
|---|---|
| Subject-Verb Agreement | Find the true subject — ignore prepositional phrases. Singular subject → singular verb. |
| Pronoun Usage | Match pronouns to antecedents in number (singular "they" for a generic person is acceptable). Use subject case (I, who) for subjects and object case (me, whom) for objects. |
| Verb Tense | Keep tenses consistent unless the time frame changes. Use past perfect for "earlier than another past event." |
| Sentence Structure | No fragments, run-ons, or comma splices. Use FANBOYS + comma, semicolons, or periods to join clauses. |
| Modifiers | The subject after an introductory phrase must be the one doing the action. |
| Parallelism | Items in a list or comparison must share the same grammatical form. |
| Confused Words | its/it's, their/there/they're, affect/effect, then/than, your/you're, who's/whose. |
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