Eliminating the Most Common Grammar Mistakes: Guide with Correct vs. Incorrect Examples

Grammar Tips

26 May 2023

This guide explains how to avoid the most common grammar mistakes in writing and helps you eliminate them. 

Most common grammar mistakes

Learning to spot grammar mistakes 

Contrary to popular belief, native English speakers can be even more prone to common grammar mistakes than ESL learners, who are relatively limited in writing skills. The reason is that most people learn the rules during primary school, which helps shape their beliefs (often learned wrong!). When there comes a time to provide an essay or conduct research, using infinitive verbs or knowing where to place commas becomes essential. 

As you learn how to detect the most common grammar mistakes in academic writing, you have to focus on editing and proofreading your writing aloud. It will help you estimate and correct issues like spelling, repetitions, style, and basic run-on sentence mistakes. Now, take your time to see what other issues can be spotted and how to get them fixed as you read on! 

20 common grammar mistakes to avoid in writing 

1. Overuse of adverbs.

This grammar mistake is quite common among modern writers who wish to express their thoughts and add more emotions to what they wish to say in writing. The adverbs are those words that usually end in "-ly", like "really", "usually, and "finally". While using them here and there may be right, they are often overdone. See some examples of correct and incorrect sentences to get a better idea. 

Incorrect: The child spoke really fast to persuade his parents. 

Correct: The child spoke hastily to persuade his parents. 

As you can see, "really fast" has been exchanged with "hastily" to identify the fast speaking speed using only one word.

2. Overuse of prepositional phrases.

While it's always stylistic, things like that are often considered a grammar issue, especially when dealing with strict academic writing. In simple terms, prepositions are those elements that usually come before nouns and pronouns. They specify direction, location, or event that has taken time. See these examples: 

Incorrect: The clouds came over the top of the house. 

Correct: The clouds covered the house’s top. 

While both sentences may sound correct, the first example is a bit wordy. It is always good to simplify your style wherever possible! 

3. Ambiguous modifiers.

Also known as the squinting modifiers, the problem relates to the misplaced modifiers. It will always depend on the word's location, which could change the phrase's meaning or modify it incorrectly. See this simple example: 

Incorrect: Playing video games slowly gives me an eye strain problem. 

Correct: I slowly develop an eye strain issue when I play video games. 

The example above makes it unclear in the first sentence whether a person is playing video games on a moderate level or becomes a headache as time unfolds. When the sentence is changed slightly (as in the correct example), it clarifies things! 

4. Misuse of verbs.

This problem is quite famous among common grammar mistakes, especially when confused between "lie" and "lay". The solution is quite clear: you must identify the situation. If one wishes to place something in a certain location (an apple on a table), it is necessary to use "lay". Now, if a dog wishes to stretch as it takes a nap, it's necessary to use the "lie" form. See the example: 

Incorrect: A dog was laying on the floor. 

Correct:  A dog was lying on the floor. 

Don't forget that the verb "lie" belongs to so-called intransitive verbs. It means that it does not need an object to pair with. If you intend to use "lay", it should have an object. The problem with these verbs is quite common! Summing things up, you can lay down your arms and finally take time to lie down and rest from the battle! 

5. Ambiguous pronoun problem.

The major problem with using pronouns in writing is that "her" and "him" may not refer to the person we think about. See this example below: 

Incorrect: Michael had to sing at the show, but couldn't make it because he was chosen as a replacement. 

Correct: Michael had to sing at the show but couldn't make it because Daniel was chosen as a replacement. 

The incorrect sentence above exemplifies a lack of a clear antecedent. As you read the "wrong" sentence, you are unsure who was chosen as a replacement and why Michael could not make it. Therefore, you have to make it clear as to who your pronouns refer to. 

6. The wrong or incorrect use of commas.

Let's start straight from the examples: 

Incorrect: He was angry, he smashed the glass. 

Correct: He was angry. Thus, he smashed the glass. 

Correct: He smashed the glass because he was angry. 

The problem relates to splice commas or cases when two independent sentences are joined incorrectly. While this problem can be easily corrected, many college and school students tend to miss the issue. 

7. Run-on sentences problem.

It's one of the most common grammar problems school teachers and college professors observe. See the examples below to compare the sentences: 

Incorrect: Tom enjoyed the movie that Andrew suggested the next evening however he likes battle movies more. 

Correct: Tom enjoyed the movie Andrew suggested the next evening; still, he likes battle movies more. 

Run-on sentences refer to cases when two separate sentences are fused together without punctuation, a period, or a semicolon. Contrary to popular belief, it's not only the case with long sentences. To avoid this problem, communicate only one idea in a sentence. If you have several ideas, use two separate sentences. 

8. Wordiness problem.

This problem is often met in research paper writing and business writing proposals. While wordiness is always subjective, splitting the sentences and making things more readable is recommended. See two examples: 

Incorrect: We have learned that your account has been blocked, and we suggest you save certain files and upload them somewhere to free up more space if you wish to receive further correspondence. 

Correct: Your account has reached the size limit. Please, free some space to continue using email. 

It's also recommended to proofread things aloud and implement the usage of strong verbs instead of adjectives and adverbs. 

9. Mixing "could of" with "could have" and using shortened words

Remember that "could of" is always wrong, although it is often used when something is being spoken. The "could have" is the correct form. It happens because the use of "could've " sounds like "could of". The majority of college students make this mistake. See the correct and incorrect examples to address this grammar error: 

Incorrect: John could of received special training and support as an Army vet, but he has ignored the opportunity. 

Correct: John could have received special training and support as an Army veteran, but he has ignored the opportunity. 

10. The tautology problem.

Let's start with examples that express the same thing but with the use of different words: 

Incorrect: Jennie made a mobile app with her own hands for accounting purposes. 

Correct: Jennie made a mobile app for accounting purposes.

Some other common grammar mistakes related to tautology include phrases like: 

Either John will eat it, or John will not eat it. 

He is crazy, or he is not crazy. 

A house is small, or a house is not small. 

A correct way with these phrases would be: 

Either John will eat it or ignore it. 

He is crazy, or he is sane. 

A house is either small or not. 

11. The use of "Its" vs. "It's".

To simplify things and avoid grammatical errors, remember that "its" is always possessive as it works as a contraction of "it is". No wonder so many students are mixing things up since we can see the "'s" part in our writing. Still, in this case, it works as a contraction. It is suggested to press "Control + F" to spot this mistake in your writing, as it can be done automatically. While it won't be considered a major mistake, knowing how to spot and correct it is still good! 

12. The incomplete comparisons problem.

Just try to spot the problem in the following sentence, and you will instantly see what's wrong with it: 

Incorrect: This social movement is better, more just, beneficial. 

Correct: This social movement proves to be better by expressing more justice and various benefits. 

The grammar errors here relate to the "wrong" sentence problem. We do not really know: better than what or what the social movement is compared to. The other sentence provides a meager explanation. 

13. Passive voice issue.

It belongs to one of those problems where it's suggested that college and school learners must use an active voice. Having a sentence with an object to work with, you can get the passive voice problem. It happens when you have an object in your sentence placed at the beginning instead of the end. It may make your writing sound unclear. 

Incorrect: My first trip to Germany will always be remembered by me. 

Correct: I will never forget my first trip to Germany. 

14. The wrong use of "they" when talking about brands.

While most native English speakers won't have this problem, it's still important to mention it. Remember that "business" or "Microsoft" is not something plural. What does it mean? It means that we should only use "it", but not "they" or "their". See these grammar mistakes examples: 

Incorrect: To keep up with their financial challenges, Microsoft has abandoned several old products. 

Correct: Microsoft has abandoned several old products to keep up with its financial challenges. 

15. The use of "affect" vs. "effect" in phrasing.

Incorrect: The painting has effected me beyond belief. 

Correct: The painting has affected me beyond belief. 

The wrong phrase speaks of an "effect". However, "effect" is not a verb per se, unlike "affect", which is! When you speak of a certain change, you can say that "a painting had a great effect on my understanding of colors". Yet, if you are not talking about the change "as such", you should use the "affect" verb. 

16. Using "me" versus "I".

Before you claim to understand the difference between these two concepts, you might need help to spot the mistake as you write. See these two examples below: 

Incorrect: When you finally finish your breakfast, can you send a copy of your assignment to Tracey and I? 

Correct: When you finish your breakfast, can you send Tracey and me a copy of your assignment? 

It's like we cannot ask another person to "send something to I" instead of "send something to me". It's a matter of proper grammar in English! 

17. Confusing the use of "i.e." and "e.g." terms. 

Most people do not remember this rule and often confuse the terms. The majority of college students tend to use them as something interchangeable, yet "i.e.," stands for "that is" or "in other words". Otherwise, "e.g." is an abbreviation for "example given" and is used when we have to provide an example. It means you should use "i.e.," when you want to clarify something and provide a better explanation. The "e.g.," part is used when you want to provide a practical example or show how something was used in real life. 

18. “Who” vs. “that” problem?

It's another challenging grammar issue in English related to the most common writing mistakes to avoid. For example: 

Larry is a person who likes to drive fast. 

As you can see from the sentence above, we are describing a person. If you talk about a living being, it should be "who". Now, when you describe an object, it's necessary to use "that, " as seen in the example below. 

John has a computer that breaks down all the time. 

19. "Loose" or "lose" problem.

It's not surprising that people often confuse "lose" and "loose" as the spelling looks quite similar! The definition of these words, however, is totally different. "Lose" stands for a verb meaning "to fail in something" or be unable to find someone as we "lose track of someone". It's like losing your baseball cap or losing in a rugby match.

If we talk about "loose", the talk goes about something that is not attached firmly or when something has become loose, like a loose tooth or a loose rope. The typical middle school trick is remembering that “if the rope is loose, you can fall and lose the competition”. 

20. “Then” or “than” issue.

ESL learners often experience this grammar problem, so we have found it important enough to mention! See the wrong and correct examples: 

Incorrect: My music taste is better then yours. 

Correct: My music taste is better than yours. 

"Than" is a special conjunction we use to compare. "Then" is an adverb pointing to an action taken during a certain period. 

Getting a quick grammar fix is possible 

As you have checked the most common grammar mistakes, it's only natural to feel confused and lost! Knowing about the issues most college and school students face, you can take an alternative way and approach a reliable grammar checker online. It's one of the best ways to eliminate grammatical mistakes and save valuable time. The report will highlight all the types of grammatical errors and help you regardless of your English level by offering suggestions and writing tips.

This solution will help you fix your spelling and develop an ESL learner. It's free to check for grammar as soon as you sign in! The best part about Fixgerald grammar checking is that you can do corrections on the spot and detect and fix plagiarism risks. You can benefit from one free check for plagiarism to eliminate risks and earn the best grades! 


  • What grammar mistakes are most common in writing? 

Among the top common grammar mistakes in English, one can spot the overuse of adverbs and prepositional phrases. Both native and ESL learners will also misuse the words like "lie" and "lay" or "regular" and "irregular" among other things. There are also run-on sentences, wordiness, and the wrong use of commas in a sentence. 

  • How can I detect grammar mistakes? 

Grammar mistakes can be detected by editing and proofreading your writing aloud. It will help you spot most writing issues and grammar mistakes if the sentence sounds odd. If you want to detect issues you may not know per se, feel free to use our amazing grammar checker online. It will help you eliminate many other types of grammar issues. 

  • What is considered a grammatical issue? 

It can be a spelling, writing, style, formatting, or any other grammar mistake, as you can learn from the most common grammar mistakes guide. 

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