Common Grammar Mistakes — Grammar Rules & Examples

What are Common Grammar Mistakes?

Grammar mistakes fall into predictable patterns. The same errors appear in IELTS Task 2, Cambridge writing papers, TOEIC responses, and everyday professional emails — regardless of the learner's first language. Knowing the patterns in advance lets you self-edit systematically rather than hoping for the best.

Most persistent errors are not random — they come from a specific misunderstanding, an overgeneralised rule, or a mismatch between the learner's first language and English. Understanding why an error happens makes it easier to correct consistently. 'Always use a/an before a noun' is an overgeneralisation that produces errors with uncountable nouns and plural nouns. Knowing the real rule replaces the false one.

This page covers the seven most common error categories at B1 level and above. Each entry names the pattern, shows the error, shows the correction, and explains the reason. For each category, there is a dedicated reference page with more detailed rules and practice exercises.

Seven Categories of Common Errors

Scan this table to identify which category an error belongs to. Then follow the link to the dedicated page for full rules and practice.

FormulaError pattern → recognition signal → correction strategy

Error Category Overview

Category	Most common error	Correction signal
Subject-verb agreement	The team have/has different opinion about this.	Identify the true subject — ignore intervening phrases
Article errors	She gave me an advice. / I need the information.	Uncountable nouns take no article or 'some'; abstract nouns often take no article
Tense and aspect	I already told you. / She is always arriving late.	Signal words: already → present perfect; always + fact → present simple
Preposition errors	She arrived to the meeting. / He is good in maths.	Most prepositions after verbs/adjectives must be memorised as collocations
Pronoun errors	It's cover was damaged. / Between you and I.	Possessive pronouns have no apostrophe; 'me' is the object case
Word form errors	She spoke very good. / He did a quick decision.	Check: modifying a verb → adverb; modifying a noun → adjective
Sentence structure errors	Although the results were good, but the sample was small.	Subordinating conjunction OR coordinating conjunction — never both

Subject-Verb Agreement Errors

Error	Correction	Rule
The quality of the reports are poor.	The quality of the reports is poor.	Subject is 'quality' (singular) — 'of the reports' is a modifier, not the subject.
Everyone have their own approach.	Everyone has their own approach.	Indefinite pronouns (everyone, nobody, each, either) are grammatically singular.
Neither of the candidates are qualified.	Neither of the candidates is qualified.	'Neither' is singular — 'of the candidates' is a modifier.

Article Errors

Error	Correction	Rule
She gave me an advice.	She gave me some advice.	'Advice' is uncountable — never takes a/an. Use 'some advice' or 'a piece of advice'.
The knowledge is power.	Knowledge is power.	Abstract nouns used in a general sense take no article.
I need an information.	I need some information.	'Information' is uncountable — never takes a/an.
She is best student in the class.	She is the best student in the class.	Superlatives require 'the'.

Tense and Aspect Errors

Error	Correction	Rule
I already told him about the change.	I have already told him about the change.	'Already' signals a present perfect context — the action has present relevance.
She is always arriving late to every meeting.	She always arrives late to every meeting.	Habitual facts and permanent states use present simple, not continuous.
By the time she arrived, he left.	By the time she arrived, he had left.	'By the time' + past → the earlier action needs past perfect.

Pronoun and Apostrophe Errors

Error	Correction	Rule
The report lost it's cover page.	The report lost its cover page.	'its' (possessive) never has an apostrophe. 'it's' = it is / it has.
Between you and I, the plan is risky.	Between you and me, the plan is risky.	Prepositions take object pronouns: me, him, her, us, them — not I, he, she, we, they.
The committee published their's findings.	The committee published its/their findings.	Possessive pronouns (its, hers, his, ours, theirs, yours) never take an apostrophe.

Correction Strategies by Error Type

Subject-verb agreement — find the true subject

The most common agreement error comes from a phrase between the subject and the verb. The verb must agree with the grammatical subject, not with the nearest noun. Identify the head noun of the subject phrase — ignore everything inside prepositional phrases.

Error: The number of applications have increased.
True subject: 'The number' (singular) — 'of applications' is a modifier.
Correct: The number of applications has increased.
Error: One of the candidates are highly qualified.
True subject: 'One' (singular) — 'of the candidates' is a modifier.
Correct: One of the candidates is highly qualified.

Tip: A reliable test: remove everything between 'of' and the verb, then check agreement. 'The number ... has' or 'The number ... have'? 'The number has' — singular. Apply the same rule to: the quality of, the majority of, a group of, one of.

Article errors — countable vs uncountable is the key

Most article errors come from treating uncountable nouns as countable (adding a/an or a plural), or from omitting 'the' when a specific, identifiable noun is being referred to. Two checks eliminate most article errors.

Uncountable — no a/an, no plural: advice, information, research, evidence, furniture, luggage, knowledge, progress, traffic, weather
Wrong: She gave me an advice → Correct: some advice / a piece of advice
Wrong: We made a progress → Correct: We made progress / some progress
Specific → use 'the': The advice she gave me was useful. (this specific advice, not advice in general)

Tip: The 'specific vs general' test: if the noun refers to a specific, identifiable instance already known to the reader, use 'the'. If it refers to the concept in general, use no article (for uncountable and plural nouns) or a/an (for singular countable nouns).

Word form errors — adjective or adverb?

Word form errors typically involve using an adjective where an adverb is needed (or vice versa), or using a noun form where a verb or adjective is required. The fix is always the same: identify the function, then choose the form that matches.

Modifying a verb → use adverb: She spoke clearly. (not 'clear')
Modifying a noun → use adjective: She gave a clear explanation. (not 'clearly')
After a linking verb (be, seem, appear, feel) → use adjective: The result seemed unusual. (not 'unusually')
Common pairs: good (adj) / well (adv) · fast (adj or adv — same form) · hard (adj or adv — same form) · late (adj or adv — same form)

Tip: The linking verb trap: 'She felt badly about the decision' is a common error. 'Felt' is a linking verb here — it connects the subject to a description of her state. The correct form is the adjective: 'She felt bad.' Use an adverb only when the verb describes an action, not a state.

Sentence structure errors — double connectors

A very common B1–B2 error is using both a subordinating conjunction (although, because, since, while) and a coordinating conjunction (but, so, yet) in the same clause. Only one connector is needed. Both together is always a grammatical error.

Error: Although the results were positive, but the sample was small.
Fix 1 (keep subordinating): Although the results were positive, the sample was small.
Fix 2 (keep coordinating): The results were positive, but the sample was small.
Error: Because the funding was cut, so the project was cancelled.
Fix 1: Because the funding was cut, the project was cancelled.
Fix 2: The funding was cut, so the project was cancelled.

Tip: The double-connector error is extremely common among speakers of East Asian and some European languages where equivalent structures require both elements. In English, one connector does the entire job. 'Although … but' is never correct.

Error Warning Signals

Phrase between subject and verb (of the / in the / with the)find the true subject before checking agreement — ignore the intervening phrase

advice / information / research / evidence / progressuncountable — no a/an, no plural, singular verb

already / just / ever / since / forpresent perfect signal — check aspect

always / usually / generally with a fact or habitpresent simple — not present continuous

Although … but / Because … sodouble connector — remove one

it's used possessivelyerror — use 'its' (no apostrophe) for possession

Between you and Ierror — prepositions take object pronouns: 'between you and me'

Double Connector Error — Although … but

This is one of the most consistent B1–B2 structural errors. One connector is correct; two connectors cancel each other out.

Double connector — incorrect

Although the evidence was strong, but the committee was not persuaded.

'Although' and 'but' both signal contrast. Only one is needed.

Single connector — correct (two versions)

Although the evidence was strong, the committee was not persuaded. / The evidence was strong, but the committee was not persuaded.

Keep 'although' (drop 'but') OR keep 'but' (drop 'although' and restructure). Not both.

Adjective vs Adverb After a Linking Verb

After action verbs, use an adverb to describe how the action is performed. After linking verbs, use an adjective to describe the subject's state.

Action verb → adverb

She presented the findings clearly.

'Clearly' modifies 'presented' (action verb) — adverb correct.

Linking verb → adjective

The findings seemed clear.

'Clear' describes the findings after the linking verb 'seemed' — adjective correct. Not 'clearly'.

Common Mistakes

Double subordinating + coordinating conjunction

✗ Although the deadline had passed, but the committee agreed to review the submission.

Although the deadline had passed, the committee agreed to review the submission.

'Although' already introduces a contrast clause. 'But' is redundant — and ungrammatical in this position. Use one connector only.

Uncountable noun treated as countable

✗ She gave me three advices. / We need more informations. / He made a progress.

She gave me three pieces of advice. / We need more information. / He made progress.

Advice, information, and progress are uncountable. They have no plural form and never take a/an. Use 'some', 'a piece of', or just the bare noun.

Possessive pronoun with apostrophe

✗ The report lost it's cover. / The company changed it's policy.

The report lost its cover. / The company changed its policy.

Possessive pronouns (its, hers, his, ours, theirs, yours) never take an apostrophe. 'It's' = 'it is' or 'it has'. Use the substitution test: if 'it is' makes sense, use 'it's'; if not, use 'its'.

Preposition error after adjectives and verbs

✗ She is good in English. / He arrived to the office at nine. / They insisted to leave early.

She is good at English. / He arrived at the office at nine. / They insisted on leaving early.

Prepositions after adjectives and verbs are collocations — fixed combinations that must be learned individually. Good at, arrived at, insist on, capable of, interested in, depend on — these cannot be predicted from the rules alone.

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