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Grammar & Sentence Structure

Study Guide

Grammar questions on the GED test your knowledge of standard English conventions. You'll need to identify and correct errors in sentence structure, punctuation, and word usage.

1Subject-Verb Agreement

The subject and verb must agree in number. Singular subjects take singular verbs; plural subjects take plural verbs. Watch out for tricky subjects with prepositional phrases between the subject and verb.

Examples:

•CORRECT: The group of students IS studying. ('group' is singular)
•CORRECT: The students ARE studying. ('students' is plural)
•INCORRECT: The box of toys are on the shelf. → IS on the shelf ('box' is the subject)
2Common Punctuation Rules

Commas: Use before 'and/but/or' in compound sentences, after introductory phrases, and to separate items in a list. Semicolons: Join two related independent clauses. Apostrophes: Show possession (dog's bone) or contractions (don't = do not).

Examples:

•I wanted to go, but it was raining. (comma before 'but' in compound sentence)
•After the meeting ended, we went to lunch. (comma after introductory phrase)
•She studied hard; therefore, she passed. (semicolon between two complete sentences)
3Commonly Confused Words

These word pairs trip up many test-takers. Learn the difference between each pair.

Examples:

•their/there/they're: their = possession, there = place, they're = they are
•its/it's: its = possession, it's = it is or it has
•your/you're: your = possession, you're = you are
•affect/effect: affect = verb (to influence), effect = noun (a result)
•then/than: then = time, than = comparison
4Run-on Sentences and Fragments

A run-on joins two sentences without proper punctuation or conjunction. A fragment is an incomplete sentence (missing a subject, verb, or complete thought).

Examples:

•RUN-ON: I love reading it is my favorite hobby. → Fix: I love reading. It is my favorite hobby.
•FRAGMENT: Because I was tired. → Fix: Because I was tired, I went to bed early.
•RUN-ON: She ran fast she won the race. → Fix: She ran fast, so she won the race.
Test-Taking Tips
Read the sentence aloud in your head — if it sounds wrong, it probably is.
Look for the subject and verb first when checking agreement.
On the GED, 'NO ERROR' is sometimes the correct answer — don't assume every sentence has a mistake.
When in doubt about comma placement, check if each part could stand alone as a complete sentence.