SAT Grammar Rules: The Short List That Covers Most Questions
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Standard English Conventions questions make up about a quarter of Reading and Writing, and unlike reading comprehension they are rule-based. Learn the rules below and most of these questions become mechanical.
Sentence boundaries
| To join two complete sentences, use… | Example |
|---|---|
| A period | The trial ended. The results surprised everyone. |
| A semicolon | The trial ended; the results surprised everyone. |
| A comma plus and, but, or, so, for, nor, yet | The trial ended, and the results surprised everyone. |
| A colon, if the second explains the first | The results were clear: the drug worked. |
A comma alone between two complete sentences is a comma splice, and nothing at all is a run-on. Both are always wrong on the SAT.
However is not a conjunction
Words like however, therefore and moreover cannot join sentences with just a comma. Write “The trial ended; however, the results…” or start a new sentence.
Commas
- Nonessential information takes a pair of commas (or dashes, or parentheses): “The river, which floods every spring, is rising.” Use the same mark at both ends.
- Essential information takes no commas: “The river that floods every spring is the Nile.”
- Never put a single comma between a subject and its verb, or between a verb and its object.
- Items in a series take commas between them; if any item contains a comma, separate the items with semicolons.
Colons and dashes
A colon must follow a complete sentence, and introduces a list, an explanation or an example. A single dash can do the same job; a pair of dashes marks off nonessential information, just like a pair of commas.
Apostrophes
| Form | Meaning |
|---|---|
| its | belonging to it |
| it's | it is / it has |
| their | belonging to them |
| they're | they are |
| the scientist's notes | one scientist |
| the scientists' notes | more than one scientist |
| the children's notes | plural not ending in s: add 's |
Agreement
- Subject–verb: find the real subject by crossing out phrases between it and the verb. “The list of items is long.”
- Pronoun–antecedent: a pronoun matches the noun it replaces. “The company released its report,” not “their report.”
- Each, every, either, neither and anyone are singular.
Verb forms and modifiers
- Keep tense consistent with the rest of the passage unless the timeline changes.
- A modifier at the start of a sentence describes whatever comes right after the comma: “Walking home, I saw the comet,” not “Walking home, the comet appeared.”
- In a list, keep every item in the same grammatical form: “to plan, to test and to publish.”
The researchers published their findings in March ______ the data had been collected over the previous two years. Which choice completes the text so that it conforms to the conventions of Standard English?
- AMarch,
- BMarch;
- CMarch, however
- DMarch, it
Explanation
Both parts are complete sentences, so they need a boundary that can join two independent clauses: a semicolon. A comma alone is a comma splice; “however” with only commas is still a splice; and “March, it” adds a pronoun that makes the sentence ungrammatical.