SAT grammar rules: a reference with examples

Joining two independent clauses

An independent clause has a subject and a verb and can stand alone. Join two of them with a full stop, a semicolon, a comma plus a coordinating conjunction (for, and, nor, but, or, yet, so), or a colon if the second explains the first.

✓ The tide was rising; the children moved their towels.
✗ The tide was rising, the children moved their towels.

The wrong sentence is a comma splice.

Transitions do not join clauses

However, therefore, moreover, for example, instead and as a result are transitions, not conjunctions. Between two clauses they need a semicolon (or a full stop) before them.

✓ The road was closed; however, the bridge was open.
✗ The road was closed, however, the bridge was open.

Colons

A colon must follow a complete independent clause. What comes after it explains, lists or names what the clause promised.

✓ She needed one thing: time.
✗ She needed: time and money.

Semicolons in complex lists

When list items already contain commas, separate the items with semicolons.

✓ They visited Lyon, France; Turin, Italy; and Basel, Switzerland.
✗ They visited Lyon, France, Turin, Italy, and Basel, Switzerland.

Extra information: matching pairs

Nonessential information inside a sentence is set off by a matching pair: two commas, two dashes or two brackets. Never mix them.

✓ The mill, built in 1782, is now a museum.
✗ The mill, built in 1782 is now a museum.

Essential information: no commas

Information that identifies which one you mean is essential and takes no commas. A title directly before a name is essential.

✓ Marine biologist Aiyana Redcloud studies octopuses.
✗ Marine biologist, Aiyana Redcloud, studies octopuses.

No comma between subject and verb

Do not put a single comma between a subject and its verb, however long the subject is.

✓ The collection of letters and photographs is online.
✗ The collection of letters and photographs, is online.

Subject-verb agreement

The verb agrees with its subject, not the nearest noun. Cross out prepositional phrases ('of the students'), 'together with' / 'as well as' phrases and relative clauses to find the subject. With 'neither... nor' and 'either... or', the verb agrees with the nearer subject.

✓ Each of the students builds a part.
✗ Each of the students build a part.

Inverted sentences

When a sentence starts with a phrase and the verb comes before the subject, find the subject after the verb.

✓ Among the finds was a brass compass.
✗ Among the finds were a brass compass.

Pronouns and antecedents

A pronoun must agree in number with the noun it refers to. Collective nouns such as committee, team and company are singular in American English.

✓ The committee announced its decision.
✗ The committee announced their decision.

Possessives and contractions

its = belonging to it; it's = it is. their = belonging to them; there = place; they're = they are. Singular possessive: scientist's. Plural possessive: scientists'.

✓ The two scientists' findings were published.
✗ The two scientist's findings were published.

Verb tense

Match tense to the time words. Use the past perfect (had + past participle) for an action completed before another past action.

✓ By the time the boat arrived, the hikers had been there for four days.
✗ By the time the boat arrived, the hikers have been there for four days.

Every sentence needs a main verb

-ing forms and to + verb are not main verbs. A sentence whose only verb is 'being' or 'to lay' is a fragment.

✓ The second was a series of reefs.
✗ The second being a series of reefs.

Dangling modifiers

An opening phrase describes the noun that comes straight after the comma. Make that noun the person or thing doing the action.

✓ Having spent three years on it, Okonkwo published the translation.
✗ Having spent three years on it, the translation was published.

Logical comparisons

Compare like with like: a bird with a bird, not a bird with a bird's nostrils.

✓ Unlike most birds, the kiwi has nostrils at the tip of its beak.
✗ Unlike most birds, the kiwi's nostrils are at the tip of its beak.

Punctuation with quotation marks (American)

In American English, commas and full stops go inside closing quotation marks. Colons and semicolons go outside.

✓ In her essay "Water and Walls," the historian argues...
✗ In her essay "Water and Walls", the historian argues...