The 5 Most Common English Grammar Mistakes (And How to Fix Them)

Introduction

After analysing thousands of learner exercises, five grammar mistakes appear again and again — in the writing of A2 beginners and B2 upper-intermediates alike. They are not random errors. They follow predictable patterns rooted in how we learn language.

This guide explains each mistake clearly, shows you why it happens, and gives you the fix — plus a practice exercise so the correction sticks.

Quick answer: The five most common English grammar mistakes are (1) present perfect vs past simple confusion, (2) missing or wrong articles, (3) subject-verb agreement errors, (4) wrong prepositions with time expressions, and (5) gerund/infinitive errors after verbs. Each one has a rule you can learn in under five minutes.

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Mistake 1: Present Perfect vs Past Simple

This is the single most common error among B1 and B2 learners.

What learners write

I have seen him yesterday. Did you ever try Thai food?

Why it happens

Many languages do not have a separate present perfect tense. Learners either translate directly from their first language or apply the simpler past simple to all past situations.

The fix

Past simple = a finished action at a specific time in the past Present perfect = a past action with a connection to now

Signal word	Tense to use
yesterday, last week, in 2020, ago	Past simple
ever, never, just, already, yet, today, so far	Present perfect

Corrected examples:

✓ I saw him yesterday. (specific past time) ✓ Have you ever tried Thai food? (life experience, no specific time)

Practice: Go to our Present Perfect vs Past Simple guide for a complete explanation and exercise.

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Mistake 2: Missing or Wrong Articles (a / an / the)

English articles are notoriously difficult — especially for speakers of Chinese, Japanese, Korean, Russian, or other languages with no article system.

What learners write

She is doctor. I bought a milk at the shop. Can you pass the salt? ✓ (this one is actually correct — and confusing to learners)

Why it happens

The rules for a/an/the/no article involve four different concepts at once: countability, specificity, shared knowledge, and register. Most learners try to memorise rules without understanding the underlying logic.

The fix

Three questions decide which article to use:

1. Is the noun countable or uncountable?

   • Countable (singular) → needs a/an or the: a book, the book
   • Uncountable → no article or some/the: milk, some milk, the milk we bought

2. Is it the first mention or a known reference?

   • First mention → a/an: I saw a dog.
   • Known reference → the: The dog barked all night.

3. Is it a general statement?

   • General → no article: Doctors need good communication skills.
   • Specific → the: The doctor I saw yesterday was excellent.

Corrected examples:

✓ She is a doctor. (any doctor, first mention of a role) ✓ I bought some milk at the shop. (uncountable, unspecified)

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Mistake 3: Subject-Verb Agreement

Simple in theory, constantly broken in practice — especially in longer sentences where the subject and verb are separated.

What learners write

The list of options are very long. A group of students were waiting outside. Everyone have a question.

Why it happens

When a prepositional phrase (of options, of students) comes between the subject and the verb, learners match the verb to the nearest noun instead of the actual subject.

The fix

Always find the head noun of the subject — the core noun, ignoring any of phrases or relative clauses — and match the verb to it.

Subject	Head noun	Correct verb
The list of options	list (singular)	is
A group of students	group (singular)	was
Everyone / anybody / nobody	always singular	has
The information	uncountable = singular	is
The team / staff / police	collective (British: plural OK)	are (British) / is (American)

Corrected examples:

✓ The list of options is very long. ✓ Everyone has a question.

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Mistake 4: Wrong Prepositions with Time Expressions

In, on, at — three tiny words that cause enormous confusion.

What learners write

I'll see you on the morning. The meeting is at Monday. She was born in 14 March.

Why it happens

Each language maps time prepositions differently. The English system (at for clock times, on for days and dates, in for months/years/periods) is logical but requires deliberate memorisation.

The fix

Preposition	Use with	Examples
at	clock times, specific moments	at 9 a.m., at noon, at midnight, at the weekend (British)
on	days, dates	on Monday, on 14 March, on my birthday, on New Year's Day
in	months, years, seasons, longer periods	in March, in 2024, in spring, in the morning, in the 20th century

Memory trick: Think of zoom levels. At = a precise point (microscope). On = a specific day (calendar). In = a broader period (telescope).

Corrected examples:

✓ I'll see you in the morning. ✓ The meeting is on Monday. ✓ She was born on 14 March.

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Mistake 5: Gerund vs Infinitive After Verbs

Some verbs are followed by a gerund (-ing form); others take an infinitive (to + verb); some take both — but with different meanings.

What learners write

I enjoy to play tennis. She avoided to make eye contact. He stopped to smoke. ✓ or ✗ — depends on meaning

Why it happens

There is no simple phonological or grammatical rule that predicts which form follows which verb. Learners must learn the patterns over time, and there are enough exceptions to make it genuinely hard.

The fix

Gerund (-ing) after: enjoy, avoid, finish, suggest, consider, keep, miss, practise, risk, imagine, can't stand, can't help

I enjoy playing tennis. She avoided making eye contact.

Infinitive (to + verb) after: want, decide, hope, plan, promise, refuse, manage, seem, need, expect, agree, offer

He decided to leave early. They refused to sign the contract.

Both — same meaning: begin, start, continue, like, love, hate, prefer

She loves reading / to read. (both correct)

Both — different meaning: stop, remember, forget, try, regret

Verb	+ gerund	+ infinitive
stop	He stopped smoking. (quit)	He stopped to smoke. (paused, in order to smoke)
remember	I remember meeting her. (past memory)	I remember to call her. (don't forget)
try	Try adding more salt. (experiment)	Try to arrive on time. (attempt)

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Practice Exercise

Correct the error in each sentence:

1. I have visited Rome last summer.
2. She is engineer at a tech company.
3. The number of applications have increased this year.
4. The event starts at Tuesday evening.
5. I look forward to hear from you.

Answers:

1. I visited Rome last summer. (specific past time → past simple)
2. She is an engineer. (singular countable job → a/an)
3. The number of applications has increased. (head noun: number, singular)
4. The event starts on Tuesday evening. (day → on)
5. I look forward to hearing from you. (look forward to = preposition + gerund)

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What to Do Next

Each of these mistakes has its own exercise on EngQuiz Pro. The fastest way to fix a grammar mistake is not to memorise the rule — it is to practice until the correct form feels wrong to skip.

Pick the mistake you make most often, do the exercise, and check back in a week.

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Frequently Asked Questions

Why do I keep making the same grammar mistakes even after I learn the rule? Knowing a rule and using it automatically are different skills. Conscious grammar knowledge takes 6–12 weeks of deliberate practice to become instinctive. The key is consistent, low-stakes practice — short exercises every day beat one long session per week.

Do native speakers make these mistakes? Yes, though they make a different set. Native speakers often confuse less/fewer, misuse apostrophes, and use double negatives informally. The mistakes in this guide are specifically patterns from learner error analysis.

Which of these mistakes matters most in a job interview or formal exam? Subject-verb agreement errors and article mistakes are the most noticeable to native speaker employers and examiners. Present perfect/past simple errors are very common and often forgiven at B1 level but penalised at B2+.