Error Detection and Common Errors

Error Detection & Common Errors

Error Detection is one of the most frequently tested areas in competitive English. Questions may ask you to identify the part of a sentence containing a grammatical error or choose the correct form of a sentence.

Most errors arise from a limited number of areas:

• • Nouns
  • Pronouns
  • Articles
  • Verbs
  • Tenses
  • Subject–Verb Agreement
  • Adjectives and Adverbs
  • Prepositions
  • Conjunctions
  • Parallel Structure

A good method is to check a sentence in this order:

Subject → Verb → Tense → Pronoun → Article → Preposition → Modifier → Conjunction → Parallelism

Noun Errors

Noun errors commonly involve:

• countable and uncountable nouns
• singular and plural forms
• irregular plurals
• collective nouns
• possessive forms
• nouns used only in singular or plural

Uncountable Nouns

Certain nouns are normally uncountable and should not be used with plural forms such as informations, advices, or furnitures.

Important examples:

• advice
• information
• furniture
• luggage
• baggage
• equipment
• machinery
• scenery
• knowledge
• evidence
• progress
• traffic
• bread
• work

Incorrect:

He gave me many advices. ✘

Correct:

He gave me much advice. ✔

or:

He gave me several pieces of advice. ✔

Incorrect:

I received many informations. ✘

Correct:

I received a lot of information. ✔

Incorrect:

The furnitures are expensive. ✘

Correct:

The furniture is expensive. ✔

Countable vs Uncountable

Use:

• many/few/a few → plural countable nouns
• much/little/a little → uncountable nouns

Incorrect:

She has much books. ✘

Correct:

She has many books. ✔

Incorrect:

There are few water left. ✘

Correct:

There is little water left. ✔

Nouns with the Same Singular and Plural Form

Some nouns have the same form in singular and plural.

Examples:

• sheep
• deer
• aircraft
• species
• series
• means

Incorrect:

Many deers were seen. ✘

Correct:

Many deer were seen. ✔

Incorrect:

These two series are interesting. ✔

Here, series remains unchanged.

Irregular Plurals

Common irregular forms include:

Incorrect:

Many childs were playing. ✘

Correct:

Many children were playing. ✔

Foreign Plurals

Traditional competitive-exam grammar often tests forms such as:

Example:

These criteria are important.

Not:

This criteria is important. ✘

In modern usage, some words such as data and media may sometimes be treated as mass nouns depending on context, but examinations often prefer the traditional distinction.

Plural-Only Nouns

Certain nouns are normally plural in form and take plural verbs.

Examples:

• scissors
• trousers
• spectacles
• binoculars
• pliers
• shorts
• clothes

Correct:

These scissors are sharp.

But:

This pair of scissors is sharp.

The verb agrees with pair, not scissors.

Singular Nouns Ending in -s

Some nouns look plural but are normally singular in meaning.

Examples:

• news
• mathematics
• physics
• economics
• politics, when referring to the subject/field
• measles

Incorrect:

The news are good. ✘

Correct:

The news is good. ✔

People and Peoples

People usually means persons collectively and takes a plural verb.

People are waiting outside.

Peoples may refer to different ethnic or national groups.

Example:

The indigenous peoples of the region have distinct traditions.

Person and Persons

Persons is possible, especially in formal or legal contexts.

In ordinary English, people is more common as the plural of person.

Collective Nouns

Words such as:

• committee
• team
• family
• jury
• audience

may take a singular verb when viewed as one unit.

Example:

The committee has submitted its report.

In British/Indian English, plural agreement may also occur when emphasis is on individual members.

Example:

The committee are divided in their opinions.

For examination purposes, determine whether the group is treated as one unit or as individual members.

Possessive Errors

For singular nouns:

Rahul’s book

For regular plural nouns ending in s:

the students’ books

For irregular plurals:

children’s toys

Incorrect:

childrens’ toys ✘

Correct:

children’s toys ✔

Joint Possession

If two people jointly possess one thing, add the apostrophe only to the second noun.

Rahul and Amit’s house

→ one house belonging jointly to Rahul and Amit

For separate possession:

Rahul’s and Amit’s houses

→ separate houses

One of + Plural Noun

Incorrect:

He is one of the best student in the class. ✘

Correct:

He is one of the best students in the class. ✔

Rule:

one of + the + superlative + plural noun

Pronoun Errors

Pronoun errors commonly involve:

• pronoun case
• pronoun–antecedent agreement
• reflexive pronouns
• relative pronouns
• distributive pronouns
• unnecessary pronouns

Subjective and Objective Case

Use subject forms as subjects:

• I
• we
• he
• she
• they
• who

Use object forms after verbs and prepositions:

• me
• us
• him
• her
• them
• whom

Incorrect:

Me and Rahul went there. ✘

Correct:

Rahul and I went there. ✔

Incorrect:

The teacher called Rahul and I. ✘

Correct:

The teacher called Rahul and me. ✔

After Prepositions

Incorrect:

Between you and I, this plan will fail. ✘

Correct:

Between you and me, this plan will fail. ✔

A pronoun after a preposition normally takes the objective case.

Who vs Whom

Use who as subject.

Who called you?

Use whom as object in formal English.

Whom did you meet?

A useful test:

• he → who
• him → whom

Example:

Whom did you invite?

→ You invited him.

Therefore, whom is correct.

Pronoun–Antecedent Agreement

A pronoun should agree with its antecedent in number and meaning.

Incorrect:

Every student must submit their form. ✘ in older traditional exam grammar

Traditional form:

Every student must submit his or her form.

Modern standard English widely accepts:

Every student must submit their form.

For competitive examinations, follow the style expected by the particular exam, but be aware that singular they is standard modern English.

Everyone/Everybody

Words such as:

• everyone
• everybody
• someone
• somebody
• anyone
• anybody
• no one
• nobody

are grammatically singular.

Example:

Everyone is ready.

Modern pronoun reference may use singular they:

Everyone should bring their ID card.

Reflexive Pronouns

Reflexive pronouns include:

• myself
• yourself
• himself
• herself
• itself
• ourselves
• yourselves
• themselves

Incorrect:

Myself Rahul. ✘

Correct:

I am Rahul. ✔

Incorrect:

Rahul and myself completed the work. ✘

Correct:

Rahul and I completed the work. ✔

Use a reflexive pronoun when the subject and object refer to the same person.

Rahul hurt himself.

Emphatic Pronouns

The same forms can add emphasis.

Example:

I myself completed the work.

But myself does not replace the normal subject pronoun.

Each Other vs One Another

Traditional grammar often distinguishes:

• each other → two
• one another → more than two

Modern usage allows considerable overlap, but competitive exams may still test the traditional distinction.

This/That and These/Those

Incorrect:

These kind of problems are difficult. ✘

Correct:

This kind of problem is difficult. ✔

or:

These kinds of problems are difficult. ✔

Relative Pronouns

Use who mainly for people.

The man who came yesterday is my uncle.

Use which mainly for things.

The book which I bought is interesting.

Use whose for possession.

The girl whose bag was lost is crying.

That in Non-Defining Clauses

Incorrect:

My brother, that lives in Delhi, is a doctor. ✘

Correct:

My brother, who lives in Delhi, is a doctor. ✔

That is not normally used in non-defining relative clauses.

One Should…One’s

Traditional formal consistency:

One should do one’s duty.

Avoid mixing:

One should do his duty. where strict formal consistency is required.

Article Errors

Articles include:

• a
• an
• the

Errors occur because of:

• sound
• specificity
• countability
• geographical names
• institutions
• superlatives
• fixed expressions

A vs An Depends on Sound

Use a before a consonant sound.

a university

because university begins with /j/ sound.

Use an before a vowel sound.

an hour

because h is silent.

Examples:

• a European
• a university
• a one-eyed man
• an honest person
• an MLA
• an MBA graduate

Singular Countable Nouns Usually Need a Determiner

Incorrect:

He is teacher. ✘

Correct:

He is a teacher. ✔

Incorrect:

I bought book. ✘

Correct:

I bought a book. ✔

Professions

Use a/an.

She is a doctor.

He is an engineer.

The with Unique Things

Examples:

the Sun

the Moon

the Earth, especially when referring to the planet as a unique object

The with Superlatives

Incorrect:

Rahul is tallest boy in the class. ✘

Correct:

Rahul is the tallest boy in the class. ✔

The with Ordinals

Examples:

the first chapter

the second question

the last opportunity

No Article with Languages and Subjects

Incorrect:

He speaks the English. ✘ when referring to the language generally

Correct:

He speaks English. ✔

Incorrect:

She studies the Geography. ✘

Correct:

She studies Geography. ✔

Meals

Normally no article:

We had breakfast at eight.

But an article may be used when the meal is specified.

The breakfast served at the hotel was excellent.

Games and Sports

Normally no article:

He plays cricket.

She likes badminton.

Institutions

When used for their primary purpose, institutions often take no article.

He goes to school every day.

But when referring to the building:

I went to the school to meet the principal.

Compare:

• go to school → as a student
• go to the school → visit the building

Similar contrasts may occur with:

• hospital
• prison
• church
• college
• bed

Usage may vary somewhat between British and American English.

Geographical Names

Use the with:

• rivers → the Ganga
• seas → the Arabian Sea
• oceans → the Indian Ocean
• mountain ranges → the Himalayas
• groups of islands → the Andaman and Nicobar Islands
• deserts → the Sahara
• plural country names → the Netherlands
• certain political names → the United States

Usually no article with:

• India
• Assam
• Asia
• Mount Everest
• Lake Superior

The + Adjective for a Class

Examples:

the rich

the poor

the elderly

These expressions refer to groups and normally take plural verbs.

The rich are not always happy.

Verb Errors

Verb errors involve:

• wrong verb form
• auxiliaries
• gerunds and infinitives
• transitive/intransitive use
• irregular verbs
• modal structures

After Do/Does/Did Use V1

Incorrect:

He did not went there. ✘

Correct:

He did not go there. ✔

Incorrect:

She does not likes coffee. ✘

Correct:

She does not like coffee. ✔

Rule:

do/does/did + V1

After Modals Use V1

Incorrect:

He can sings well. ✘

Correct:

He can sing well. ✔

Incorrect:

You should to work hard. ✘

Correct:

You should work hard. ✔

Rule:

modal + V1

Exception-like structures with ought to, have to, etc. contain to as part of their own construction.

After Have/Has/Had Use V3

Incorrect:

She has went home. ✘

Correct:

She has gone home. ✔

Incorrect:

He had wrote the letter. ✘

Correct:

He had written the letter. ✔

Continuous Tenses Use V-ing

Incorrect:

He is play football. ✘

Correct:

He is playing football. ✔

Gerund after Prepositions

Incorrect:

He is interested in learn English. ✘

Correct:

He is interested in learning English. ✔

Incorrect:

She left without say anything. ✘

Correct:

She left without saying anything. ✔

To as Preposition

Some expressions contain to as a preposition and therefore require a noun or gerund.

Examples:

• look forward to
• object to
• be accustomed to
• be used to
• committed to
• devoted to

Incorrect:

I look forward to meet you. ✘

Correct:

I look forward to meeting you. ✔

Used to

Past habit:

used to + V1

Incorrect:

I used to playing cricket. ✘

Correct:

I used to play cricket. ✔

But:

I am used to playing cricket. ✔

Had Better

Incorrect:

You had better to leave. ✘

Correct:

You had better leave. ✔

Would Rather

Incorrect:

I would rather to stay home. ✘

Correct:

I would rather stay home. ✔

Let and Make

Active:

let + object + V1

make + object + V1

Incorrect:

Let him to go. ✘

Correct:

Let him go. ✔

Incorrect:

The teacher made him to write. ✘

Correct:

The teacher made him write. ✔

But passive:

He was made to write. ✔

Suggest

Incorrect:

He suggested me to go there. ✘

Correct:

He suggested going there. ✔

or:

He suggested that I go there. ✔

Enjoy/Avoid/Mind

These are commonly followed by gerunds.

Incorrect:

She enjoys to read novels. ✘

Correct:

She enjoys reading novels. ✔

Incorrect:

Avoid to make mistakes. ✘

Correct:

Avoid making mistakes. ✔

Lie vs Lay

lie = recline

Forms:

lie – lay – lain

lay = put/place something

Forms:

lay – laid – laid

Examples:

He lay on the bed yesterday.

She laid the book on the table.

Rise vs Raise

rise → intransitive

raise → transitive

Examples:

The Sun rises in the east.

They raised the price.

Incorrect:

The price was risen by the company. ✘

Correct:

The company raised the price. ✔

Tense Errors

Tense errors occur when time references and verb forms do not agree logically.

Since/For with Perfect Tenses

Incorrect:

I am living here since 2020. ✘

Correct:

I have been living here since 2020. ✔

Incorrect:

I have lived here since five years. ✘

Correct:

I have lived here for five years. ✔

Remember:

• since → point of time
• for → duration

Ago Requires Simple Past

Incorrect:

He has left two hours ago. ✘

Correct:

He left two hours ago. ✔

Ago normally refers to a completed past time.

Yesterday/Last Week with Simple Past

Incorrect:

I have met him yesterday. ✘

Correct:

I met him yesterday. ✔

A specific finished past time generally requires Simple Past.

Already/Yet with Perfect Tense

Common patterns:

I have already finished the work.

I have not finished the work yet.

However, already can also occur with Simple Past, especially in American English and certain contexts.

Present Perfect vs Simple Past

Incorrect:

I have visited Delhi in 2022. ✘ if 2022 is a finished past period

Correct:

I visited Delhi in 2022. ✔

Present Perfect generally avoids a specific finished past-time reference.

Past Perfect for Earlier Past

Example:

When I reached the station, the train had left.

The train left first.

I reached later.

The earlier action is expressed by Past Perfect.

Future Time Clauses

Incorrect:

I will call you when I will reach home. ✘

Correct:

I will call you when I reach home. ✔

After:

• when
• before
• after
• until
• as soon as
• unless
• if

ordinary future meaning is usually expressed with a present tense in the subordinate clause.

First Conditional

Incorrect:

If you will work hard, you will succeed. ✘ in an ordinary condition

Correct:

If you work hard, you will succeed. ✔

Third Conditional

Incorrect:

If I would have known, I would have helped. ✘

Correct:

If I had known, I would have helped. ✔

It Is Time/High Time

Incorrect:

It is high time you start working. ✘ in traditional examination grammar

Correct:

It is high time you started working. ✔

Wish

Present unreal:

I wish I knew the answer.

Past regret:

I wish I had known the answer.

Agreement Errors

Subject–Verb Agreement means that the verb should agree with the subject in number and person.

Singular Subject Takes Singular Verb

Incorrect:

He go to school every day. ✘

Correct:

He goes to school every day. ✔

Plural Subject Takes Plural Verb

Incorrect:

The boys plays cricket. ✘

Correct:

The boys play cricket. ✔

Intervening Phrase Does Not Change Agreement

Incorrect:

The quality of these products are excellent. ✘

Correct:

The quality of these products is excellent. ✔

Subject = quality, not products.

Along With/As Well As

Incorrect:

Rahul, along with his friends, are coming. ✘

Correct:

Rahul, along with his friends, is coming. ✔

The verb agrees with Rahul.

The same principle applies to:

• together with
• accompanied by
• as well as
• in addition to
• including

Either…Or / Neither…Nor

In traditional examination grammar, the verb generally agrees with the nearer subject.

Either Rahul or his friends are coming.

Either his friends or Rahul is coming.

Similarly:

Neither the teachers nor the principal is present.

Each/Every

Incorrect:

Each student have a book. ✘

Correct:

Each student has a book. ✔

Incorrect:

Every boy and every girl are ready. ✘

Correct:

Every boy and every girl is ready. ✔

Each of

Incorrect:

Each of the students are present. ✘

Correct:

Each of the students is present. ✔

One of

Incorrect:

One of my friends are a doctor. ✘

Correct:

One of my friends is a doctor. ✔

A Number of

A number of + plural noun + plural verb

Example:

A number of students are absent.

The Number of

The number of + plural noun + singular verb

Example:

The number of students is increasing.

Many a

Many a + singular noun + singular verb

Example:

Many a student has failed to understand this rule.

More Than One

Traditional rule:

More than one + singular noun + singular verb

Example:

More than one student has complained.

Amounts and Measurements

When considered as one unit:

Ten kilometres is a long distance to walk.

Five years is a long time.

Ten thousand rupees is a large amount for him.

The Rich/The Poor

These expressions represent groups and take plural verbs.

The poor need support.

Relative Pronoun Agreement

Example:

He is one of the students who work hard.

Here, who refers to students, so work is plural.

But:

He is the only one of the students who works hard.

Here, who refers to the only one, so works is singular.

Adjective/Adverb Errors

An adjective modifies a noun or pronoun.

An adverb normally modifies a verb, adjective or another adverb.

Adjective vs Adverb

Incorrect:

She sings beautiful. ✘

Correct:

She sings beautifully. ✔

The word modifies the verb sings, so an adverb is required.

After Linking Verbs

After linking verbs such as:

• be
• seem
• appear
• look
• feel
• smell
• taste
• sound
• become

an adjective is often required when describing the subject.

Incorrect:

She looks beautifully. ✘ if describing her appearance

Correct:

She looks beautiful. ✔

But:

She looked carefully at the painting.

Here looked means directed her eyes, so carefully is an adverb.

Good vs Well

good → adjective

well → usually adverb

Examples:

She is a good singer.

She sings well.

But well can also be an adjective meaning healthy.

I am well today.

Hard vs Hardly

hard = with great effort

hardly = almost not

Examples:

He works hard.

He hardly works.

These meanings are very different.

Late vs Lately

late = after the expected time

lately = recently

Examples:

He arrived late.

I haven’t seen him lately.

Near vs Nearly

near = close

nearly = almost

Examples:

Come near.

The work is nearly complete.

High vs Highly

high may indicate physical height.

The bird flew high.

highly often means greatly or favourably.

He is highly respected.

Too vs Very

Incorrect:

The tea is very hot to drink. ✘ if meaning excessively hot

Correct:

The tea is too hot to drink. ✔

Very intensifies.

Too indicates excess.

Enough

Incorrect:

He is enough strong to lift it. ✘

Correct:

He is strong enough to lift it. ✔

Rule:

adjective/adverb + enough

But:

enough + noun

Example:

We have enough money.

Comparative Errors

Incorrect:

She is more taller than her sister. ✘

Correct:

She is taller than her sister. ✔

Avoid double comparison.

Incorrect:

This is the most easiest question. ✘

Correct:

This is the easiest question. ✔

Senior/Junior/Superior/Inferior

These adjectives traditionally take to, not than.

Incorrect:

He is senior than me. ✘

Correct:

He is senior to me. ✔

Similarly:

• junior to
• superior to
• inferior to
• prior to

Preferable

Incorrect:

This method is preferable than that. ✘

Correct:

This method is preferable to that. ✔

Preposition Errors

Preposition errors are extremely common because many combinations are fixed by usage.

At/In/On for Time

Use:

at → exact time

at 5 p.m.

on → days/dates

on Monday

on 5 September

in → months, years, longer periods

in September

in 2026

At/In/On for Place

at → point/specific location

at the station

in → inside an area/space

in Delhi

in the room

on → surface

on the table

Since vs For

Incorrect:

He has lived here since five years. ✘

Correct:

He has lived here for five years. ✔

Between vs Among

Traditional distinction:

between → commonly two

among → more than two

Examples:

Divide the money between Rahul and Amit.

The teacher distributed sweets among the students.

Modern English can use between with more than two when individual relationships are involved, but examinations may prefer the traditional rule in straightforward questions.

Beside vs Besides

beside = next to

besides = in addition to

Example:

She sat beside me.

Besides English, she knows Hindi.

In vs Into

in indicates position.

The boy is in the room.

into indicates movement towards the inside.

The boy went into the room.

On vs Onto

on → position

The book is on the table.

onto → movement to a surface

The cat jumped onto the table.

By vs With

by often introduces the agent.

The novel was written by Orwell.

with often indicates an instrument.

He cut the fruit with a knife.

Married To

Incorrect:

She is married with a doctor. ✘

Correct:

She is married to a doctor. ✔

Agree With/To/On

agree with → a person/opinion

I agree with you.

agree to → a proposal/plan/terms

They agreed to the proposal.

agree on → reach a shared decision about something

They agreed on a date.

Depend On

Incorrect:

Success depends of hard work. ✘

Correct:

Success depends on hard work. ✔

Insist On

He insisted on paying the bill.

Not:

He insisted to pay the bill. ✘ in this structure

Prevent From

The rain prevented us from playing.

Accuse Of

The police accused him of theft.

Congratulate On

I congratulated her on her success.

Apologise For

He apologised for being late.

Interested In

She is interested in history.

Good At

He is good at mathematics.

Afraid Of

The child is afraid of dogs.

Proud Of

She is proud of her daughter.

Discuss

Discuss normally does not require about before its direct object.

Incorrect:

We discussed about the issue. ✘

Correct:

We discussed the issue. ✔

But:

We had a discussion about the issue. ✔

Enter

Incorrect:

He entered into the room. ✘ in the ordinary sense of going inside

Correct:

He entered the room. ✔

However, enter into is correct in certain meanings:

They entered into an agreement.

Reach

Incorrect:

We reached at the station. ✘

Correct:

We reached the station. ✔

But:

We arrived at the station. ✔

Mention

Incorrect:

He mentioned about the problem. ✘

Correct:

He mentioned the problem. ✔

Conjunction Errors

Conjunction errors commonly involve:

• incorrect pairings
• double conjunctions
• conditionals
• contrast
• cause and result

Although/Though…But

Incorrect:

Although he was poor, but he was honest. ✘

Correct:

Although he was poor, he was honest. ✔

or:

He was poor, but he was honest. ✔

Because…So

Incorrect:

Because he was ill, so he stayed home. ✘

Correct:

Because he was ill, he stayed home. ✔

or:

He was ill, so he stayed home. ✔

No Sooner…Than

Incorrect:

No sooner had he arrived when it started raining. ✘

Correct:

No sooner had he arrived than it started raining. ✔

Hardly/Scarcely…When

Incorrect:

Hardly had he arrived than the train left. ✘

Correct:

Hardly had he arrived when the train left. ✔

Remember:

• No sooner → than
• Hardly → when
• Scarcely → when

Either…Or

Correct:

Either Rahul or Amit will attend.

Do not incorrectly mix pairs:

Either Rahul nor Amit… ✘

Neither…Nor

Correct:

Neither Rahul nor Amit was present.

Not Only…But Also

Correct:

She is not only intelligent but also hardworking.

Incorrect:

She is not only intelligent but she is hardworking also. ✘ when strict parallel structure is expected

Both…And

Correct:

Both Rahul and Amit attended the meeting.

Not:

Both Rahul as well as Amit… ✘

Unless

Incorrect:

Unless you do not study, you will fail. ✘ if the intended meaning is if you do not study

Correct:

Unless you study, you will fail. ✔

Until

Unlike unless, until can naturally occur with a negative main clause.

Correct:

I will not leave until he returns.

If vs Whether

Use whether when alternatives are explicitly expressed.

I don’t know whether he will come or not.

Also preferred:

It depends on whether he agrees.

So…That

Correct:

He was so tired that he fell asleep.

Such…That

Correct:

It was such a difficult question that nobody answered it.

Incorrect:

It was so difficult question that… ✘

Correct:

It was such a difficult question that… ✔

Despite vs Although

Incorrect:

Despite he was ill, he came. ✘

Correct:

Although he was ill, he came. ✔

or:

Despite being ill, he came. ✔

Because vs Because Of

because + clause

because of + noun/noun phrase

Incorrect:

Because of he was ill, he stayed home. ✘

Correct:

Because he was ill, he stayed home. ✔

or:

Because of his illness, he stayed home. ✔

Parallelism

Parallelism means using the same grammatical form for words, phrases or clauses that perform the same function in a sentence.

Parallel structure makes a sentence clear, balanced and grammatically consistent.

Items in a Series

Incorrect:

She likes reading, swimming and to dance. ✘

Correct:

She likes reading, swimming and dancing. ✔

All three items use V-ing.

Alternatively:

She likes to read, to swim and to dance. ✔

With And

Incorrect:

He is intelligent, hardworking and has honesty. ✘

Correct:

He is intelligent, hardworking and honest. ✔

All three elements are adjectives.

With Both…And

Incorrect:

She is both intelligent and works hard. ✘

Correct:

She is both intelligent and hardworking. ✔

or:

She both studies hard and works efficiently. ✔

With Either…Or

Incorrect:

You can either stay here or going home. ✘

Correct:

You can either stay here or go home. ✔

With Neither…Nor

Incorrect:

He neither likes reading nor to write. ✘

Correct:

He likes neither reading nor writing. ✔

or:

He neither reads nor writes. ✔

With Not Only…But Also

Incorrect:

She not only sings well but also a good dancer. ✘

Correct:

She is not only a good singer but also a good dancer. ✔

Another:

She not only sings well but also dances beautifully. ✔

Comparisons Require Parallel Structure

Incorrect:

The salary of a doctor is higher than a teacher. ✘

This compares salary with teacher.

Correct:

The salary of a doctor is higher than that of a teacher. ✔

Another:

Incorrect:

The population of Delhi is greater than Mumbai. ✘

Correct:

The population of Delhi is greater than that of Mumbai. ✔

Like Should Be Compared with Like

Incorrect:

Rahul’s marks are higher than Amit. ✘

Correct:

Rahul’s marks are higher than Amit’s. ✔

The comparison is:

marks ↔ marks

not:

marks ↔ Amit

Than I/Than Me

Both forms can occur depending on structure and style.

Formal:

She is taller than I am.

Informal:

She is taller than me.

For competitive exams, the fully expressed form than I am is often safer when pronoun case is specifically being tested.

Correlative Conjunction Placement

Correlative conjunctions should be placed before grammatically parallel elements.

Weak:

She not only bought a laptop but also a phone.

Better:

She bought not only a laptop but also a phone.

Here, both correlated items are noun phrases.

Another:

She not only sang but also danced.

Here, both are verbs.

Infinitive Parallelism

Correct:

The aim is to educate, to inspire and to empower students.

Also acceptable:

The aim is to educate, inspire and empower students.

Once to applies to all coordinated verbs, unnecessary repetition is not required.

Gerund Parallelism

Correct:

The job involves planning, organising and supervising projects.

Incorrect:

The job involves planning, organising and to supervise projects. ✘

Clause Parallelism

Incorrect:

The teacher said that students should work hard and punctuality was important. ✘ if the intended ideas are coordinated in the same grammatical pattern

Better:

The teacher said that students should work hard and that they should be punctual. ✔

Common Parallelism Patterns

Common Error Detection Traps

A sentence may appear correct because each individual word seems acceptable, but the relationship between the words may be wrong.

Common traps include:

• uncountable noun used in plural
• singular subject with plural verb
• incorrect pronoun case
• missing article before a singular countable noun
• wrong form after did
• wrong V3 after has/have/had
• future tense inside an ordinary future time clause
• wrong preposition after an adjective or verb
• incorrect correlative conjunction
• non-parallel items in a series
• double comparative
• incorrect relative pronoun
• unnecessary preposition
• incorrect gerund/infinitive pattern

Error Detection Checklist

When solving an error-detection question, check the sentence systematically:

• Noun
  • Is it countable or uncountable?
  • Is the number correct?
  • Is the plural form correct?
• Pronoun
  • Is the case correct?
  • Does it agree with its antecedent?
  • Is the relative pronoun correct?
• Article
  • Does the singular countable noun need a/an/the?
  • Is the choice based on sound?
  • Is an article unnecessarily used?
• Verb
  • Is the correct verb form used?
  • Does the auxiliary require V1/V3/V-ing?
• Tense
  • Does the tense match the time reference?
  • Is the sequence of actions logical?
• Agreement
  • What is the true subject?
  • Is an intervening phrase misleading you?
• Adjective/Adverb
  • What exactly is being modified?
  • Is a linking verb involved?
• Preposition
  • Is the correct fixed combination used?
  • Is the preposition unnecessary?
• Conjunction
  • Is the pair correct?
  • Is there an unnecessary double conjunction?
• Parallelism
  • Are coordinated words or phrases in the same grammatical form?

Revision Table

Key Points to Remember

• Advice, information, furniture, luggage, equipment and evidence are normally uncountable.
• Write:
  • much advice
  • a piece of advice
  • not advices
• Remember:
  • one of the best students
  • one of my friends
• After prepositions, use objective pronouns:
  • between you and me
• Reflexive pronouns cannot normally replace ordinary subject pronouns:
  • Rahul and I, not Rahul and myself
• Article choice depends on sound, not spelling:
  • a university
  • an hour
• A singular countable noun generally requires a determiner:
  • He is a teacher.
• After do/does/did, use V1:
  • did go
  • does work
• After has/have/had, use V3:
  • has gone
  • had written
• After ordinary modals, use V1:
  • can go
  • should study
• After a preposition, normally use:
  • noun
  • pronoun
  • V-ing
• Remember:
  • look forward to meeting
  • interested in learning
  • without speaking
• Used to + V1
  • used to play
• Be used to + V-ing
  • used to playing
• Had better + V1
  • had better leave
• Would rather + V1
  • would rather stay
• Time clues matter:
  • yesterday/ago/last year → usually Simple Past
  • since/for with continuing situations → commonly Perfect/Perfect Continuous
• Do not normally write:
  • when I will reach
  • if you will work
• Write:
  • when I reach
  • if you work
• Find the real subject before choosing the verb:
  • The quality of the products is good.
• Remember:
  • each/every → singular
  • a number of → plural verb
  • the number of → singular verb
• Use:
  • senior to
  • junior to
  • superior to
  • inferior to
  • preferable to
• Do not use unnecessary prepositions:
  • discuss the issue
  • enter the room
  • reach the station
  • mention the problem
• Remember conjunction pairs:
  • either…or
  • neither…nor
  • both…and
  • not only…but also
  • no sooner…than
  • hardly/scarcely…when
• Avoid:
  • although…but
  • because…so
  • despite of
• Parallel items should have the same grammatical form:
  • reading, writing and speaking
  • intelligent, honest and hardworking
  • to study, to practise and to revise

The key to error detection is not to read a sentence only for meaning. A sentence can sound natural and still contain a grammatical error. Instead, examine the relationship between the subject and verb, noun and determiner, pronoun and antecedent, verb and auxiliary, adjective and noun, verb and preposition, conjunction pair, and coordinated structures. Once these recurring patterns are mastered, a large proportion of competitive-exam error-detection questions can be solved quickly and accurately.