Conventions of Standard English

Complete sentences, fragments and run-ons

An independent clause has a subject, a verb, and a complete thought — it could stand alone as a sentence.

• Fragment: a piece of a sentence that is missing a subject, a verb, or a complete thought (“Because the bus was late.”).
• Comma splice: two independent clauses joined by only a comma. This is the single most common ACT error.
• Run-on: two independent clauses jammed together with no punctuation at all.
• Four legal ways to join two independent clauses: a period; a semicolon; a comma + FANBOYS (for, and, nor, but, or, yet, so); or make one clause dependent with a word like because, although, when, which.
• Words like however, therefore and also are NOT FANBOYS. “…, however, …” between two complete sentences is still a comma splice — use “; however,”.

Semicolons, colons and dashes

• Semicolon (;) works like a period: it needs a complete sentence on BOTH sides. (Rare exception: separating list items that already contain commas.)
• Colon (:) needs a complete sentence BEFORE it. After it comes a list, an explanation, or an example. Never put a colon right after a verb or a preposition (“The recipe needs: flour” is wrong).
• Single dash (—) can work like a colon to set off something at the end of a sentence.
• Pair of dashes works like a pair of commas around extra information. Don’t mix one dash with one comma.

Commas

• When FANBOYS joins two parts of a sentence, use a comma before it only if both parts are complete sentences. No comma when the second part has no subject: “She studied and passed” (not “studied, and passed”). (Lists of three or more are different — see below.)
• Use a comma after an introductory word, phrase or dependent clause: “After the game, we ate.”
• Nonessential information (you could delete it and the sentence still makes sense and keeps its meaning) goes between TWO commas — or none, if it is essential.
• Essential information gets no commas: “Students who finish early may leave.” Only the students who finish early may leave, so the clause is essential.
• Commas separate items in a list of three or more: “red, white, and blue.”
• Never put a single comma between a subject and its verb, between a verb and its object, or right before “that.”

Apostrophes and possessives

• Singular owner: add ’s — the dog’s bowl. Plural owner ending in s: add just ’ — the dogs’ bowls. Plural not ending in s: add ’s — the children’s books.
• Plain plurals never get an apostrophe: “three apples,” not “three apple’s.”
• its = belonging to it; it’s = it is / it has. Same pattern: their / they’re / there, whose / who’s, your / you’re.
• Test: if you can expand it to “it is,” use it’s. If not, use its.

Subject–verb agreement

• Find the real subject. Cross out prepositional phrases (“of the books,” “in the drawers”) — the subject is never inside one.
• Each, every, either, neither, one, anyone, everybody → singular verb.
• Two subjects joined by “and” → plural. Joined by “or/nor” → the verb matches the closer subject.
• In “There is / There are” sentences, the subject comes AFTER the verb: “There are three reasons.”

Verb tense and verb forms

• Keep tense consistent with the rest of the paragraph unless the timeline actually changes.
• After has / have / had, use the past participle: had gone (not had went), has written (not has wrote), had swum, had broken.
• Use “had + participle” (past perfect) for something that happened before another past event: “By the time we arrived, the movie had started.”
• “Would have,” “could have,” “should have” — never “would of.”

Pronouns

• Agreement: a pronoun matches its noun in number. A company, team, or city is singular → it / its.
• Case: subject pronouns (I, he, she, we, they, who) do the action; object pronouns (me, him, her, us, them, whom) receive it or follow a preposition.
• Trick for pairs: cover up the other person. “Give it to Sam and I” → “give it to I” sounds wrong → “Sam and me.”
• Who vs. whom: if you could answer with he → who; with him → whom.
• Clear reference: if “she” or “it” could point to two different nouns, the ACT wants the noun spelled out.

Modifiers and parallel structure

• An introductory describing phrase must be followed immediately by the thing it describes. Otherwise it is a dangling modifier.
• Adjectives describe nouns (a quick runner); adverbs describe verbs and adjectives (she ran quickly).
• Compare two things with -er / more; three or more with -est / most.
• Parallelism: items in a list or pair must have the same form — “to swim, to bike, and to run,” not “to swim, biking, and to run.”