Top 10 Grammar Mistakes ESL Writers Must Fix in 2025

Clear, accurate grammar is essential for any student aiming to boost their IELTS, TOEFL, or PTE Academic writing scores in 2025. Whether you are writing a Task 2 essay, an independent opinion piece, or responding to an academic discussion, even small grammar errors can make your writing hard to understand and lower your band score. The good news? Fixing the most common grammar mistakes can lead to quick, dramatic improvement-often within just a few weeks of focused practice.

In this comprehensive guide, you'll learn about the top 10 grammar mistakes ESL writers must fix when preparing for high-stakes English exams. We'll explain what each mistake is, why it matters, and how you can avoid it in your own writing. You'll find exam-specific tips, clear examples, and realistic correction strategies to help you write with confidence. And if you want instant, personalized feedback, remember that you can try Essay Tutor, which provides automatic error correction and phrasing suggestions tailored for TOEFL, IELTS, and PTE tasks.

Let's dive into the essential grammar errors you need to conquer for exam and real-world success in 2025.

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1. Subject-Verb Agreement Errors

What's the mistake?
The verb in your sentence must agree with its subject in number (singular or plural). This is especially confusing when the subject is separated from the verb, when you use collective nouns, or when sentences get more complex in IELTS or TOEFL essays.

Common error:

• Incorrect: He have a pet dog.
• Correct: He has a pet dog.

Why it matters:
Subject-verb agreement is the foundation of clear communication and one of the first things exam raters notice.

How to fix:

• Always find the subject first. Ignore extra phrases between the subject and verb.
• For present simple, add '-s' or '-es' to the verb for third-person singular subjects (he, she, it).
• With collective nouns ("team," "group"), decide if you mean as a single unit (singular) or individuals (plural).
• Check every sentence for agreement before moving on.

Exam tip:
If you're writing under time pressure, underline or highlight your subjects when proofreading your draft.

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2. Run-On Sentences

What's the mistake?
A run-on occurs when two complete sentences (independent clauses) are joined without proper punctuation or conjunctions.

Common error:

• Incorrect: The line was long I decided to come back later.
• Correct: The line was long. I decided to come back later.
  or The line was long, so I decided to come back later.

Why it matters:
Run-ons confuse your reader and make your logic unclear-both are major issues in exam scoring frameworks.

How to fix:

• Break into two sentences: Add a period.
• Use a coordinating conjunction: (for, and, nor, but, or, yet, so).
• Use a semicolon: Only if the relationship between ideas is clear.

Exam tip:
When reviewing, check for sentences that seem too long and look out for missing punctuation or conjunctions.

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3. Sentence Fragments

What's the mistake?
A fragment is a group of words missing a subject, verb, or complete idea.

Common error:

• Incorrect: Because students are busy.
• Correct: Because students are busy, they often procrastinate.
  or Students are busy.

Why it matters:
Fragments weaken your argument and make your essay seem underdeveloped or confusing.

How to fix:

• Ensure every sentence has a subject and a verb and expresses a complete thought.
• Attach fragments to nearby sentences if they rely on them for meaning.

Exam tip:
Practice identifying fragments in your own essays-especially after using linking words like "because," "although," and "if."

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4. Incorrect Tense Usage

What's the mistake?
Using the wrong verb tense confuses when actions happened-past, present, or future.

Common error:

• Incorrect: Yesterday, I go to the library and study for the test.
• Correct: Yesterday, I went to the library and studied for the test.

Why it matters:
Inconsistent verb tense will lower clarity, one of the key criteria for TOEFL and IELTS writing tasks.

How to fix:

• Signal words: Look for time markers (yesterday, now, by next year) and match your tense.
• Essay introductions: Use present tense to state facts, but switch to past/present perfect when describing personal experiences.

Exam tip:
Highlight time phrases in your essay plan and revise all verbs to match.

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5. Article Mistakes (a, an, the)

What's the mistake?
English uses articles ("a," "an," "the") in ways that can be confusing for learners from article-free languages.

Common errors & quick rules:

• General, countable, singular: a or an
  She bought a car. (any car)
• Vowel sound: use an
  an apple, an hour
• Specific/known to both speaker and listener: the
  I closed the door. (the only one here/known door)
• Plural or uncountable nouns, in general: no article
  Cats are popular pets. Information is important.

Why it matters:
Misusing articles is a common mistake that immediately marks your writing as "non-native" and can delay understanding.

How to fix:

• Practice with article exercises featuring common nouns and exam vocabulary.
• Build a routine: always check your singular countable nouns for missing articles.

Exam tip:
For IELTS/TOEFL essays: explain a general concept? Use no article. Describing something specific? Use "the."

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6. Preposition Misuse

What's the mistake?
Using the wrong or redundant prepositions, or omitting them where needed.

Common error:

• Incorrect: She discussed about the issue.
• Correct: She discussed the issue.

Other typical confusions:

• Good at math (not "good in math")
• Dependent on something (not "dependent of")
• Arrived at the station (not "arrived to the station")

Why it matters:
Prepositions change meaning and fluency. Regular errors affect grammar and vocabulary scores in exams.

How to fix:

• Memorize common verb + preposition collocations.
• Double-check which prepositions are required-and which are not!

Exam tip:
Keep a list of common prepositions with exam-related verbs (discuss, depend, focus, arrive, etc.).

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7. Plural Forms & Uncountable Noun Errors

What's the mistake?
Incorrectly adding "-s" to uncountable nouns (informations, advices) or forming irregular plurals incorrectly.

Common errors:

• Incorrect: He gave me many advices.
  Correct: He gave me much advice.
• Incorrect: I need two informations.
  Correct: I need two pieces of information.

Other examples:

• Incorrect: Childs → Correct: Children
• Incorrect: Furnitures → Correct: Furniture (uncountable)

Why it matters:
These errors signal to examiners that your vocabulary knowledge isn't accurate enough for high-level scores.

How to fix:

• Learn which nouns are uncountable in English (information, advice, furniture, news, equipment, research).
• Study irregular plural forms (children, mice, men, women).

Exam tip:
When in doubt, look up the word, or use countable structures ("a piece of advice") for uncountable nouns.

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8. Misplaced Modifiers

What's the mistake?
A misplaced modifier is a word or phrase placed too far from what it describes, causing confusion or humor.

Common error:

• Incorrect: Walking down the street, the trees looked beautiful.
  (sounds like the trees were walking!)
• Correct: Walking down the street, I noticed the trees looked beautiful.

Why it matters:
Clarity is critical for exam tasks. Misplaced modifiers can make your points unclear or even misleading.

How to fix:

• Place modifying phrases close to the words they describe.
• Grammar check: ask, "Who/what is doing the action?" If the answer is not immediately after the modifier, revise.

Exam tip:
Look carefully at any introductory clause-does it match the subject that follows?

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9. Wrong Comparative Structures

What's the mistake?
Writing "more + -er" (e.g., more easier, more faster) or misusing comparatives and superlatives.

Common error:

• Incorrect: This task is more easier than the last one.
• Correct: This task is easier than the last one.

Other common points:

• Use "more" for longer adjectives: more interesting, more comfortable
• Use "-er" for short adjectives: faster, older, bigger
• For superlatives: the best, the most effective

Why it matters:
Incorrect comparatives are penalized in both grammar and vocabulary sections.

How to fix:

• Short adjectives: add -er (tall → taller)
• Long adjectives (usually 2+ syllables): use more/most (more useful, most comfortable)
• Never use double comparatives ("more easier," "most fastest").

Exam tip:
When you finish writing, scan for all "more/most" and "-er/-est" forms-check if you have doubled them up.

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10. Confusing Word Forms (Adjective vs. Adverb)

What's the mistake?
Mixing up adjectives (describe nouns) and adverbs (describe verbs, adjectives, or other adverbs).

Common error:

• Incorrect: He did good on his exam.
• Correct: He did well on his exam.

More examples:

• She is a quick runner. (quick = adjective for runner/noun)
• She runs quickly. (quickly = adverb for runs/verb)

Why it matters:
Mistakes here make your writing sound unnatural. Adverb/adjective errors affect fluency and clarity ratings.

How to fix:

• Remember: adjectives describe things (nouns), adverbs describe actions (verbs), or adjectives/other adverbs.
• Many adverbs end in "-ly," but watch for exceptions ("fast" is both adjective and adverb).

Exam tip:
When writing about how something is done, double-check if you need an adverb ("-ly") instead of an adjective.

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How to Avoid These Mistakes: Practical Practice Strategies

Now that you know the top 10 grammar mistakes ESL writers must fix in 2025, set yourself up for success with these universal exam-preparation tips:

1. Proofread with a Goal

Don't just read-look for one error type at a time (e.g., only subject-verb agreement, then only article errors, etc.). This makes hidden issues easier to catch.

2. Use Model Essays

Review high-scoring responses for your target test (IELTS, TOEFL, PTE), paying attention to grammar in complex and simple sentences. Copy and adapt example structures for your own practice.

3. Get Instant, Targeted Feedback

Automated platforms like Essay Tutor are perfect for exam preparation. Paste your essay and get instant grammar correction, wording improvement, and band/score insights. This allows you to spot habits quickly and track your progress-saving you weeks of frustration.

4. Build an Error Log

Keep a notebook or digital document listing:

• Types of errors you make
• The correct form
• A model sentence for practice

Review this log before every new writing session.

5. Simulate Exam Conditions

Regularly write essays under timed conditions and follow with focused proofreading on the errors above. The more you practice under pressure, the less likely you'll be to make common mistakes in the real exam.

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Frequently Asked Questions (FAQs)

Why do these grammar mistakes lower my IELTS/TOEFL scores?
Examiners assess grammar under strict criteria. Frequent mistakes reduce your coherence, clarity, and precision, resulting in lower grammar and task achievement scores.

What's the fastest way to fix these errors?
Regular, focused practice combined with instant correction feedback (such as provided by Essay Tutor) produces the fastest results.

Are grammar mistakes more serious than vocabulary errors?
Both are important, but grammar problems often make it hard for the reader to understand your main ideas, which is heavily penalized.

Can grammar check tools help me?
Absolutely! Automated tools help you see your problem patterns and suggest native-like alternatives. However, always review the flagged sentences to understand the reasons behind the corrections.

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Conclusion: Take Control Of Your Grammar-And Your Exam Success

Fixing these top 10 grammar mistakes is the most efficient, high-impact step you can take on your journey to IELTS, TOEFL, or PTE writing mastery in 2025. Clarity, accuracy, and variety in grammar not only boost your band scores-they make your writing persuasive and easy to follow for any international audience.

Start by reviewing your own essays for these specific errors. Write, revise, and check your work with purposeful intention. And if you want a smarter, faster way to master exam grammar, let Essay Tutor guide you with instant feedback, real exam prompts, and targeted improvement advice.

Remember: Most students improve quickest when they focus on common error patterns. A single week spent mastering these grammar points can raise your essay from "unclear" and "average" to "clear," "correct," and "exam-ready."

You've got this!
Ready to see your writing mistakes disappear? Try Essay Tutor today and take your next essay from good to great.