SAT® & ACT® Grammar Rules 2 - Apostrophes and Punctuation

Aug 25, 2026

A focused SAT® and ACT® grammar guide that teaches punctuation and related sentence structures through clear rules and example corrections. Covers apostrophes for nouns and pronouns, semicolons versus periods, and essential comma usage with FANBOYS conjunctions. Includes guidance on common test pitfalls such as sentence boundaries and frequently confused forms like it’s/its, they’re/their/there, and who’s/whose, with emphasis on how to apply the rules to select correct answers under exam conditions.

LanguageEnglish

CategoryExam

FormatPDF

Pages28

Reading Time1 h 11 min

AccessFree to download

Apostrophes

Apostrophes with Nouns

Apostrophes with Pronouns

Semicolons and Periods

Semicolon vs Period

Commas

Comma with Coordinating Conjunctions (FANBOYS)

Complete SAT® & ACT® Grammar Rules e-book Table of Contents I. Apostrophes 2 II. Semicolons and Periods 4 III. Commas 6 Iv. Colons 11 V. Dashes 12 VI. Shorter is Better 13 VII. Parallel Structure 13 VIII. Subject-Verb Agreement 14 IX. Pronoun Agreement 15 X. Verb Tense 16 XI.Adjectives vs. Adverbs 17 XII. Word Pairs 18 XIII. Who , Which , and Whom 19 XIV. Dangling and Misplaced Modifiers 19 XV. Pronoun Case 20 XVI. Idioms and Diction 21 XVII. Transitions 23 © 2018 The Critical Reader Complete SAT/ACT Grammar Rules 2 ________________________________________________________________________ I. Apostrophes A. Apostrophes with Nouns Apostrophes make nouns possessive. To make singular noun possessive , add apostrophe + -s. • The boy’s coat = the coat belonging to the boy This rule holds true even when a singular noun ends in-s. • The dress’s buttons = the buttons on the dress To make a plural noun possessive , add-s + apostrophe. • The books' pages = the pages of the books If the singular form of a noun ends in-s , add-es + apostrophe to the make the plural form possessive. • The dresses' buttons = the buttons on the dresses Some nouns are irregular—that is , their plural versions are not formed by adding-s to their singular forms , e.g. , foot, feet; goose , geese; child, children. To form the possessive of such nouns , add apostrophe + -s. Because the plural form is already different from the singular form , the two types of possessivescan be easily distinguished. • The goose's feathers = the feathers of the goose (sing.) • The geese's feathers = the feathers of the geese (pl.) • The child's game = the game the child is playing (sing.) • The children’s game = the game the children are playing (pl.) Complete SAT/ACT Grammar Rules 3 B. Apostrophes with Pronouns No apostrophe = possessive It’s vs. Its It’s = it is Its = possessive of it; followed by a noun Its’& its’s = do not exist Incorrect: London is a city known for it’s (it is) many tourist attractions. Correct: London is a city known for its many tourist attractions. Incorrect: London is a popular tourist attraction; in fact, its among the most visited cities in the world. Correct: London is a popular tourist attraction; in fact, it’s among the most visited cities in the world. Note that on the ACT, the correct answer is almost always its because this is the form students tend to misuse most frequently. They’re vs. Their vs. There They’re = they are Their = possessive of they and plural of its; followed by a noun There = a place Correct: London and Paris are two of the most famous cities and Europe, and they’re (they are) known for having many tourist attractions. Correct: London and Paris, two of the most famous cities in Europe, are known for their many tourist attractions. Correct: In the nineteenth century, Paris was considered the capital of theart world because so many famous painters lived and worked there. Complete SAT/ACT Grammar Rules 4 ________________________________________________________________________ Who’s vs. Whose Who’s = Who is Correct: Barbara McClintock is a scientist who’s (who is) best known for her discovery of “jumping” genes. Whose = Possessive of who; followed by a noun Correct: Barbara McClintock is a scientist whose discovery of "jumping"genes helped earn her the 1983 Nobel Prize in Physiology or Medicine. Note that whose , unlike who , can be used for both people and things/places. Correct: London is a city whose many museums , palaces , and monuments make it a popular tourist destination. II. Semicolons and Periods A. Semicolon = Period Semicolons and periods are used: 1. Between two complete sentences Correct: London is an old city; it was first settled around 47 A. D. 2. Before conjunctive adverbs such as however, moreover, and therefore when they are used to begin a clause.* Correct: London is an ol

FAQs

How do you form singular and plural possessive nouns with apostrophes?

For singular nouns, add apostrophe + -s. For plural nouns, add -s + apostrophe; if the singular ends in -s, use -es + apostrophe for the plural possessive.

When should you use a semicolon instead of a period on the SAT/ACT?

Use a semicolon between two complete sentences, and before conjunctive adverbs such as however, moreover, or therefore when they start a clause.

What are the key comma rules with FANBOYS conjunctions?

Use a comma before a coordinating conjunction (For, And, Nor, But, Or, Yet, So) to join two complete sentences; conjunctions like and and but are especially common in test questions.

Aug 25, 2026

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