Common English Grammar Mistakes

Grammar errors can diminish the impact of your document. Grammar mistakes distract readers, causing them to focus on the errors rather than on the content of your document. They can even change the meaning of your sentences. Set aside time to review your writing to spot common grammar mistakes, and you'll produce a cleaner document that is more effective and easier to understand.

Mixed-Up Homonyms

Homonyms are words that you pronounce the same but spell differently. They also have different meanings. Mixing up homonyms is a common grammar pitfall. Writers often confuse "your" with "you're." Your is the possessive form of you, whereas you're is a contraction meaning "you are." In the following sentence, these homonyms are used properly: It's your birthday, and you're going to celebrate. "It's" and "its" are another set of confusing homonyms. It's is a contraction meaning "it is." Its is a possessive pronoun. For example, It's an old knife, so its blade is dull.

Subject-Verb Agreement

Lack of subject-verb agreement is a common grammar mistake. Make sure that your nouns and verbs agree in number, according to the Purdue Online Writing Lab. If the subject is plural, the verb should be plural; if the subject is singular, it takes a singular verb. Keep your eye out for prepositional phrases in between the noun and verb---they often can lead to subject-verb agreement mistakes. For example, in the following sentence, the noun (number) takes a singular verb even though the word following it (opportunities) is plural: The number of opportunities to go on vacation is decreasing.

Lack of Parallel Structure

Parallel structure means that items in a series take the same form. Items in a series can all be nouns, gerunds, or verb phrases, for instance. In the following sentence, the activities are not in parallel structure: Kate likes to hike, swim, and going biking. You can revise this sentence to be parallel by changing "going biking" to "bike." Check for parallel structure in all lists in your document, especially bulleted or numbered lists.


Writers often insert apostrophes incorrectly in their writing. Apostrophes have two uses---to form a contraction and to indicate possession for nouns, according to the University of Wisconsin Writing Center. This sentence displays the proper use of apostrophes: Mary's car won't last much longer. Do not use apostrophes to make a noun plural.

Comma Splices

Writers often use commas to separate independent clauses not joined by a conjunction, which creates the grammatically incorrect comma splice. Instead, use semicolons to separate two independent clauses not joined by a conjunction. Independent clauses are those clauses that can stand alone as a complete sentence. For example, in the following sentence, use a semicolon to separate the clauses: Jack loves riding his bike; he uses it for exercise.

About the Author

Barbie Carpenter worked as a technical writer and editor in the defense industry for six years. She also served as a newspaper feature page editor and nationally syndicated columnist for the Hearst Corp. Carpenter holds a Bachelor of Science in journalism from the University of Florida and a graduate certificate in professional writing from the University of Central Florida.

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