Common English Grammar Mistakes: Examples, Corrections, and How to Avoid Them

Good grammar helps readers understand your writing without having to stop and interpret what you mean. Yet even experienced writers can make common grammar mistakes, especially when writing quickly, working in a second language, or switching between formal and informal communication. A sentence may look correct at first glance while containing an error in subject-verb agreement, punctuation, verb tense, or word usage.

Recognising these errors is the first step toward avoiding them. The Trinka Grammar Checker can also help identify grammar, spelling, and usage issues while you write, giving you an additional layer of review before you share or submit your work. However, understanding why an error is incorrect is just as important because it helps you make better decisions in future writing.

1. Subject-Verb Agreement Errors

The subject and verb in a sentence need to agree in number. A singular subject generally takes a singular verb, while a plural subject takes a plural verb. This becomes particularly easy to miss when other words appear between the subject and the verb.

Incorrect: The list of required documents are on the desk.

Correct: The list of required documents is on the desk.

The subject is “list,” not “documents,” so the singular verb “is” is required. To avoid this common grammar mistake, identify the main subject before choosing the verb. This is especially useful in longer sentences where additional phrases can make the sentence structure less obvious.

2. Incorrect Use of Apostrophes

Apostrophes are commonly used to show possession or form contractions, but they are often placed incorrectly. One frequent mistake is using an apostrophe to create a plural noun.

Incorrect: The student submitted three paper’s.

Correct: The student submitted three papers.

For possession, the apostrophe has a different function.

Incorrect: The students assignment was incomplete.

Correct: The student’s assignment was incomplete.

When a noun is plural and already ends in “s,” possession is usually shown by placing the apostrophe after the “s.”

Example: The researchers’ findings were published.

Checking whether an apostrophe is being used for possession, contraction, or incorrectly for a plural can help prevent this error.

3. Confusing “Your” and “You’re”

“Your” and “you’re” sound alike but have different meanings. “Your” shows possession, while “you’re” is the contraction of “you are.”

Incorrect: Your going to need more time.

Correct: You’re going to need more time.

Another example is:

Incorrect: I like your explanation because you’re examples are clear.

Correct: I like your explanation because your examples are clear.

A simple way to check this is to replace “you’re” with “you are.” If the sentence still makes sense, “you’re” is probably correct. If it does not, “your” may be the right choice.

4. Using the Wrong Verb Tense

Verb tense tells readers when an action happened. Switching between tenses without a reason can make writing confusing, particularly when describing events in sequence.

Incorrect: She completed the experiment and writes the results in her report.

Correct: She completed the experiment and wrote the results in her report.

The sentence refers to two completed actions in the past, so both verbs should use the past tense. However, tense changes can be correct when the meaning requires them.

Example: She completed the experiment and now writes the results in her report.

Here, “completed” refers to a past action, while “writes” describes what she is doing now. The key is to make sure every tense change reflects a genuine change in time or meaning.

5. Confusing “There,” “Their,” and “They’re”

These three words are pronounced similarly but serve different grammatical purposes.

There generally refers to a place or introduces a statement.

Example: The report is over there.

Their shows possession.

Example: The researchers submitted their report.

They’re is short for “they are.”

Example: They’re reviewing the results.

Because these words sound alike, relying only on pronunciation can lead to mistakes. Instead, consider the role of the word in the sentence before selecting it.

6. Sentence Fragments

A complete sentence normally needs a subject and a finite verb and should express a complete thought. A sentence fragment may contain some of these elements but fail to communicate a complete idea.

Incorrect: Because the results were inconsistent.

Correct: The researchers repeated the experiment because the results were inconsistent.

The first example begins with a dependent clause but does not complete the thought. Fragments can occur when writers separate a dependent clause from the main sentence during editing. Reading each sentence independently can help you identify whether it expresses a complete thought.

7. Misplaced or Dangling Modifiers

A modifier should clearly describe the word or phrase it is intended to modify. When its position creates an unclear or unintended meaning, the sentence becomes difficult to interpret.

Unclear: After reviewing the report, several errors were found.

The sentence appears to suggest that “several errors” reviewed the report. A clearer version is:

Correct: After reviewing the report, the researcher found several errors.

Placing the person or thing performing the action immediately after the introductory phrase usually makes the intended meaning clearer.

8. Confusing “Affect” and “Effect”

“Affect” is most commonly used as a verb meaning to influence, while “effect” is most commonly used as a noun referring to a result or consequence.

Incorrect: The lack of sleep can effect your concentration.

Correct: The lack of sleep can affect your concentration.

Example: The lack of sleep had a noticeable effect on her concentration.

There are exceptions to these general patterns, but understanding their most common uses can prevent many everyday errors. When uncertain, consider whether you need a word describing an action or the result of that action.

9. Incorrect Pronoun Usage

Pronouns need to agree with their antecedents and fit correctly within the sentence. Problems often occur when writers use a pronoun that does not clearly refer to a specific noun.

Unclear: When the manager spoke to the researcher, he was concerned about the results.

It is unclear whether “he” refers to the manager or the researcher.

Clearer: The manager was concerned about the results when he spoke to the researcher.

Rewriting the sentence can remove ambiguity instead of forcing the reader to determine what the pronoun means.

10. Run-On Sentences and Comma Splices

A run-on sentence occurs when independent clauses are incorrectly joined without appropriate punctuation or a conjunction. A comma splice occurs when two independent clauses are joined only with a comma.

Incorrect: The study was completed, the researchers began analysing the data.

Correct: The study was completed, and the researchers began analysing the data.

Another option is to separate the ideas.

Correct: The study was completed. The researchers began analysing the data.

If a sentence contains several complete thoughts, check whether they have been joined correctly. Breaking a long sentence into shorter ones can often make the writing clearer.

How to Avoid Common Grammar Mistakes

Avoiding common grammar mistakes is less about memorising every grammar rule and more about developing a consistent review process. Start by reading your writing slowly after drafting it. Look specifically for subject-verb agreement, verb tense, pronoun references, punctuation, and commonly confused words rather than trying to identify every possible problem at once.

It also helps to read sentences according to their meaning rather than simply how they sound. Ask whether the subject is clear, whether the verb matches it, whether each pronoun has a clear reference, and whether the punctuation accurately separates ideas. Reading your work aloud can also reveal missing words, awkward sentence structures, and unnecessary repetition.

For longer or important documents, an automated grammar review can providec another layer of checking. Trinka Grammar Checker can help identify grammar and language issues while you write, allowing you to review suggested corrections before finalising your document. The goal is not simply to remove errors but to develop a stronger understanding of the patterns behind them.

Final Thoughts

Common grammar mistakes can affect clarity even when the underlying idea is strong. Errors involving subject-verb agreement, apostrophes, verb tenses, pronouns, modifiers, and commonly confused words are particularly easy to overlook during everyday writing.

The best approach is to combine grammatical awareness with careful revision. Understand why a correction is needed, review sentences in context, and use grammar-checking tools as an additional review step. Over time, recognising these patterns becomes easier, making your writing clearer, more accurate, and easier for readers to follow.