25 Common English Grammar Mistakes and the Correct Ways to Use Them

English grammar mistakes can make a sentence confusing, unnatural, or difficult to understand. Even learners who know many English words may struggle with subject-verb agreement, verb tenses, articles, prepositions, pronouns, and sentence structure. These errors can appear in school assignments, job applications, emails, interviews, presentations, and everyday conversations.

The good news is that many common English grammar mistakes follow predictable patterns. Once you understand why a sentence is incorrect and how to correct it, you can apply the same principle to other sentences. For example, learning why we say “She doesn’t understand” instead of “She don’t understand” helps you form other negative sentences correctly.

This article explains 25 common English grammar mistakes and the correct ways to use the relevant words and sentence structures. Each mistake includes an incorrect example, a corrected version, and an explanation of the rule. You will also find practical assignments and a detailed answer key to help you test your understanding.

Whether you are a beginner or an intermediate English learner, the goal is to help you recognise grammatical errors, correct your own writing, and communicate more accurately and confidently.

1. Subject-Verb Agreement Mistakes

Subject-verb agreement means using a verb form that matches its subject in number and person. In the present simple tense, singular third-person subjects such as he, she, it, and singular nouns usually take a verb ending in -s or -es. Plural subjects generally use the base form of the verb.

For example, “She works in a bank” is correct, while “She work in a bank” is incorrect in standard English. The subject she requires works. However, we say “They work in a bank” because they takes the base form. This distinction is particularly important when describing routines, habits, and facts.

The verb be follows a different pattern. We say “I am ready,” “He is ready,” and “They are ready.” Similarly, have becomes has with a third-person singular subject in the present simple: “She has a car,” but “They have a car.”

One common difficulty occurs when extra words appear between the subject and the verb. In “The basket of apples is on the table,” the subject is basket, not apples. The verb must agree with the main subject rather than a nearby noun. Identifying the subject before choosing the verb is a useful way to avoid this mistake.

Assignment 1: Practise subject-verb agreement

Instructions: Choose the correct verb or rewrite the sentence correctly.

1. My sister (study / studies) English every evening.

2. The children (was / were) excited about the trip.

3. Everyone (need / needs) enough time to prepare.

4. Correct this sentence: “The manager of the offices are absent.”

5. Complete the sentence: “My friends and I ___ (enjoy) reading.”

2. Using the Wrong Verb Tense

Verb tense helps communicate when an action or situation occurs. English has present, past, and future forms, along with patterns that show whether an action is habitual, ongoing, completed, or connected to another time. Choosing the wrong tense can make the timing of an event unclear.

The present simple is commonly used for routines, habits, and general facts. For example, “I walk to work every morning” describes a regular activity. The present continuous, formed with am, is, or are plus a verb ending in -ing, often describes an activity happening now or a temporary situation: “I am walking to work now.”

The past simple describes completed events in the past. For example, “We visited our uncle yesterday.” Because yesterday identifies a finished past time, the past simple is appropriate. Saying “We visit our uncle yesterday” mixes a present-tense verb with a past-time expression.

The present perfect connects a past event to the present. For example, “I have finished my assignment” emphasises the present relevance of the completed work. When a sentence identifies a finished time such as last week or in 2022, the past simple is generally the appropriate choice: “I finished my assignment last week.”

Assignment 2: Choose the correct tense

1. My father usually ___ (drives / is driving) to work.

2. Please wait. I ___ (talk / am talking) to my supervisor.

3. They ___ (arrive / arrived) yesterday.

4. Correct this sentence: “She has completed the course last month.”

5. Write one sentence about a daily habit and one about something happening now.

3. Using the Wrong Form After Do, Does, or Did

The helping verbs do, does, and did are used to form many questions and negative statements. When one of these helping verbs carries the grammatical marking, the main verb usually remains in its base form. The base form is the simplest form of the verb, such as go, eat, work, or understand.

For example, the statement “He likes football” becomes “He does not like football.” The form does already indicates the third-person singular present tense, so the main verb changes from likes to like. The same principle applies to questions: “Does he like football?”

In the past simple, did carries the past-tense marking. Therefore, we say “Did you see the message?” and “I did not see the message.” We do not normally say “Did you saw the message?” or “I did not saw the message” in standard English because the past tense is being marked twice.

This rule applies to many common verbs and is especially useful in conversation. Whenever you use do, does, or did as a helping verb, check that the main verb is in its base form.

Assignment 3: Correct the verb forms

1. Correct this sentence: “He doesn’t understands the question.”

2. Choose the correct form: “Did you (eat / ate) breakfast?”

3. Correct this sentence: “Does your brother plays tennis?”

4. Complete the sentence: “We did not ___ (receive / received) your email.”

4. Confusing Is, Am, Are, Was, and Were

The verb be is one of the most frequently used verbs in English. It can connect a subject to a description, identify someone or something, or help form continuous verb tenses. Its form changes according to the subject and, in many cases, the time being described.

In the present tense, use am with I, is with singular third-person subjects, and are with you, we, they, and plural nouns. For example, “I am tired,” “She is tired,” and “They are tired.” These forms cannot be exchanged freely because each has a particular grammatical role.

In the past tense, was is used with I, he, she, it, and singular nouns. Were is used with you, we, they, and plural nouns. For example, “The teacher was absent” and “The teachers were absent.”

The verb be is also used in continuous tenses. We say “He is working,” “They are studying,” and “I was sleeping.” Do not add am, is, or are before a main verb unless the sentence structure requires it. For example, “I am agree” is incorrect because agree is already a verb. The correct sentence is “I agree.”

Assignment 4: Practise the verb be

1. I ___ happy to meet you. (am / is)

2. The students ___ in the library yesterday. (was / were)

3. Correct this sentence: “My parents is at home.”

4. Correct this sentence: “She is understand the lesson.”

5. Complete the sentence: “When I called him, he ___ sleeping.” (was / were)

5. Omitting or Misusing Articles: A, An, and The

Articles are words placed before many nouns to show whether the speaker means something general or something identifiable. The articles a and an are indefinite articles, while the is the definite article. Choosing the correct article depends on the noun’s grammatical form, its first sound, and the meaning of the sentence.

Use a or an with a singular countable noun when referring to something that is not yet identified or does not need to be identified precisely. For example, “I bought a notebook” introduces a notebook without assuming the reader knows which one. Use a before a consonant sound and an before a vowel sound. This is a rule about pronunciation, not simply spelling.

For example, we say “a university” because university begins with a /y/ sound, but “an umbrella” because umbrella begins with a vowel sound. We also say “an hour” because the h is silent. Learning to listen for the first sound helps you choose the correct article even when spelling is misleading.

Use the when the person or thing is identifiable from the conversation or situation. For example, “I saw a dog outside. The dog was barking.” The first sentence introduces a dog, and the second refers to that same dog. Articles are often omitted when making general statements with plural countable nouns or uncountable nouns, as in “Books are useful” and “Water is essential.”

Assignment 5: Practise article usage

1. She wants to become ___ engineer. (a / an)

2. He is ___ European visitor. (a / an)

3. Correct this sentence: “Please give me an information.”

4. Complete the sentence: “I saw a man at the gate. ___ man was carrying a bag.”

5. Write two sentences introducing an object with a or an and then referring to the same object with the.

6. Confusing Countable and Uncountable Nouns

Countable nouns refer to things that can be counted individually, such as book, chair, and student. They can be singular or plural: one book, two books. Uncountable nouns refer to substances, materials, or ideas that are not normally counted as separate units in their usual meanings. Examples include water, furniture, information, advice, and equipment.

The distinction matters because countable and uncountable nouns behave differently. A singular countable noun generally needs a determiner, such as a, the, this, or my. We say “I bought a chair,” not usually “I bought chair.” Uncountable nouns do not normally take a or an in their ordinary meanings, so we say “I bought some furniture.”

To count an uncountable noun, you can use a unit or container. For example, instead of “two breads,” you might say “two loaves of bread” or “two slices of bread.” Instead of “three informations,” say “three pieces of information.” These expressions make the units countable while keeping the original noun in its usual form.

Some nouns can be countable or uncountable depending on their meaning. Chicken can refer to meat, as in “We ate chicken,” or individual birds, as in “There are six chickens in the yard.” Coffee is usually uncountable when referring to the drink generally, but “two coffees” can mean two servings in a café.

Assignment 6: Countable or uncountable?

1. Choose the correct expression: (many / much) information.

2. Correct this sentence: “I bought two breads.”

3. Complete the sentence: “We need three ___ of paper.” (sheets / papers)

4. Choose the correct sentence:

   • A. She gave me an advice.

   • B. She gave me a piece of advice.

5. Write one sentence using furniture and one using chairs.

7. Using the Wrong Preposition

A preposition is a word that shows a relationship involving place, time, direction, method, or another connection. Common prepositions include in, on, at, to, from, with, for, and by. Some prepositions follow predictable patterns, while others are part of fixed expressions that learners need to practise.

For time, in is commonly used with months, years, and longer periods, as in “in April” and “in 2026.” On is commonly used with days and dates, as in “on Friday” and “on April 12.” At is commonly used with clock times, as in “at 8 a.m.” These are useful general patterns, although certain expressions have their own conventions.

For place, in often means inside an area or enclosed space, as in “in the room.” On commonly refers to a surface, as in “on the desk.” At often identifies a point or location, as in “at the entrance.” The correct choice depends on the meaning you want to express, not just the name of the place.

Some prepositions are linked to particular adjectives and verbs. Standard expressions include interested in, good at, afraid of, depend on, and listen to. Translating these expressions word for word from another language can lead to errors. Learning the complete phrase helps you remember the correct preposition.

Assignment 7: Choose the correct preposition

1. My birthday is ___ July. (in / on)

2. The meeting starts ___ 9 a.m. (at / in)

3. She is interested ___ learning French. (in / on)

4. Correct this sentence: “I listened the teacher carefully.”

5. Complete the sentence: “We have lived here ___ five years.” (for / since)

8. Confusing Subject and Object Pronouns

Pronouns replace nouns or refer to people and things already mentioned. They help prevent repetition, but the form of a pronoun depends on its role in the sentence. Subject pronouns include I, you, he, she, it, we, and they. Object pronouns include me, you, him, her, it, us, and them.

Use a subject pronoun when it performs the action or serves as the subject. For example, “She called the office” and “They arrived early.” Use an object pronoun when it receives an action or follows a preposition: “The manager called her” and “The message is for them.”

A common difficulty occurs when two people are named together. In standard English, we say “James and I attended the meeting” because the pronouns form part of the subject. We say “The manager spoke to James and me” because the pronouns follow the preposition to. A helpful technique is to remove the other person’s name temporarily and see which pronoun fits.

Possessive forms need similar care. Use my, your, his, her, its, our, and their before a noun, as in “their house.” Use mine, yours, his, hers, and ours when the possessive form stands alone, as in “The house is theirs.”

Assignment 8: Choose the correct pronoun

1. My brother and ___ went to the market. (I / me)

2. The coach congratulated ___ after the match. (they / them)

3. This is ___ classroom. (our / ours)

4. Correct this sentence: “The principal invited my friend and I.”

5. Write a sentence using they as a subject pronoun and another using them as an object pronoun.

9. Confusing Your and You’re

Your and you’re sound the same in many varieties of English, but they have different grammatical functions. Your is a possessive determiner, which means it shows that something belongs or relates to the person being addressed. For example, “Your application has been received” refers to the application associated with the reader.

You’re is a contraction of you are. It is used wherever the words you are would make sense. For example, “You’re doing well” means “You are doing well.” A simple test is to replace you’re with you are. If the sentence still makes sense, you’re is likely correct.

The confusion often appears in short messages and emails because the two words sound alike. However, using the wrong form can make professional writing appear careless. Read the sentence for meaning rather than relying on pronunciation alone.

Assignment 9: Your or you’re?

1. ___ invited to the meeting. (Your / You’re)

2. Please bring ___ notebook tomorrow. (your / you’re)

3. Correct this sentence: “Your doing a great job.”

4. Write one sentence using your and another using you’re.

10. Confusing There, Their, and They’re

There, their, and they’re are often confused because they sound alike in many accents. However, each word serves a different purpose. There can refer to a place, as in “Put the bag there,” or introduce the existence of something, as in “There is a problem.”

Their is a possessive determiner. It shows that something belongs or relates to a group of people or things: “Their house is near the school.” They’re is a contraction of they are, as in “They’re waiting outside.” Understanding the meaning of each word is more reliable than trying to distinguish them by sound.

A useful correction technique is to substitute a phrase. If you can replace the word with they are, use they’re. If the sentence expresses ownership, use their. If it refers to a location or introduces existence, there may be the correct choice.

Assignment 10: Choose the correct word

1. ___ going to arrive soon. (There / Their / They’re)

2. The children packed ___ lunch boxes. (there / their / they’re)

3. Correct this sentence: “Their are two emails for you.”

4. Write one sentence each with there, their, and they’re.

11. Confusing Its and It’s

The words its and it’s have different grammatical functions. Its is a possessive form used to show that something belongs or relates to an animal, object, organisation, or other entity. For example, “The company changed its opening hours.” The word its refers to the company.

It’s is a contraction of it is or it has. For example, “It’s cold today” means “It is cold today,” while “It’s been a difficult week” means “It has been a difficult week.” The apostrophe indicates that letters have been omitted.

This pair confuses learners because possessive nouns often use apostrophes, as in “the student’s book.” However, possessive pronouns and possessive forms such as its, hers, ours, and theirs do not use apostrophes. The easiest test is to replace it’s with it is or it has and check whether the sentence still makes sense.

Assignment 11: Its or it’s?

1. ___ a beautiful morning. (Its / It’s)

2. The bird spread ___ wings. (its / it’s)

3. Correct this sentence: “Its been a long day.”

4. Write one sentence using its and another using it’s.

12. Confusing Adjectives and Adverbs

An adjective describes a noun or pronoun, while an adverb often describes a verb, an adjective, another adverb, or an entire statement. These word classes may look similar, but they do different jobs. In “She is a careful driver,” the adjective careful describes the driver. In “She drives carefully,” the adverb carefully describes how she drives.

Many adverbs are formed by adding -ly to an adjective, as in slow/slowly and careful/carefully. However, not every adverb ends in -ly. Words such as fast, hard, and late can function as adverbs: “He runs fast,” “She works hard,” and “We arrived late.”

Some words ending in -ly, such as friendly and lovely, are adjectives. You can say “a friendly neighbour” or “a lovely day,” but you would normally say “He spoke in a friendly way” rather than “He spoke friendly” in standard English.

The adjective good and the adverb well also need attention. We say “She is a good singer,” but “She sings well.” In the first sentence, good describes a person or role. In the second, well describes the quality of the singing.

Assignment 12: Adjectives or adverbs?

1. The student answered the question ___. (correct / correctly)

2. She is a ___ speaker. (confident / confidently)

3. Correct this sentence: “He speaks English fluent.”

4. Choose the correct sentence:

   • A. The soup smells delicious.

   • B. The soup smells deliciously.

5. Write a sentence using an adjective and another using an adverb formed from the same word.

13. Using Double Comparatives and Superlatives

Comparative adjectives compare two people or things. Short adjectives often form the comparative by adding -er, as in tall/taller and small/smaller. Longer adjectives commonly use more, as in more useful and more comfortable. The correct form depends partly on the adjective’s spelling and syllable pattern.

Superlative adjectives compare one person or thing with a whole group. Short adjectives commonly take -est, as in tall/tallest, while longer adjectives often use most, as in most useful and most comfortable. Some adjectives have irregular forms, including good/better/best and bad/worse/worst.

A common mistake is using two comparative markers together. For example, “more easier” is incorrect because easier is already the comparative form of easy. The correct sentence is “This exercise is easier than the previous one.” Similarly, “the most tallest student” should be “the tallest student.”

Not every comparison uses the same structure. We normally use than after a comparative when identifying the person or thing being compared: “This road is wider than that road.” A superlative commonly takes the when identifying the top member of a group: “This is the widest road in the area.”

Assignment 13: Correct the comparisons

1. This bag is ___ than that one. (lighter / more lighter)

2. Correct this sentence: “He is the most strongest player.”

3. Complete the sentence: “This is the ___ solution of all.” (best / better)

4. Write one comparative sentence and one superlative sentence.

14. Incorrect Word Order in Questions

English questions often use a different word order from statements. In a statement such as “You are ready,” the subject comes before the verb. To form a question, move the verb are before the subject: “Are you ready?” This pattern is common with the verb be and with sentences that already contain a helping verb.

When a sentence uses the present simple or past simple with most other verbs, questions usually require do, does, or did. For example, “She works here” becomes “Does she work here?” and “They visited yesterday” becomes “Did they visit yesterday?” The main verb returns to its base form after does or did.

Information questions begin with words such as who, what, where, when, why, and how. For example, “Where do you live?” asks for a place, while “Why did she leave?” asks for a reason. In most such questions, the helping verb comes before the subject.

There is an important exception when the question word itself is the subject. For example, “Who called you?” is correct without do because who performs the action. Compare this with “Who did you call?” where you is the subject and who is the object.

Assignment 14: Form correct questions

1. Change this statement into a question: “She is at home.”

2. Correct this question: “Where they live?”

3. Choose the correct sentence:

   • A. Did you finish the work?

   • B. Did you finished the work?

4. Write a question asking why someone arrived late.

5. Write one question in which who is the subject.

15. Using Much and Many Incorrectly

Much and many both refer to quantity, but they are used with different types of nouns. Use many with plural countable nouns, such as books, students, questions, and cars. Use much with uncountable nouns, such as time, money, water, and information.

For example, “How many students attended the lecture?” is correct because students can be counted individually. “How much time do we have?” is correct because time is uncountable in this meaning. Using the wrong word can make the sentence grammatically incorrect or unnatural.

In everyday affirmative statements, a lot of and lots of are commonly used with both countable and uncountable nouns. For example, “We have a lot of books” and “We have a lot of work.” Much is especially common in questions and negative sentences, as in “How much money do you need?” and “We don’t have much time.”

Some nouns can be countable or uncountable depending on their meaning. For example, experience can mean knowledge gained over time, as in “She has a lot of experience,” or individual events, as in “She had several interesting experiences.” The meaning of the noun determines which quantity expression is appropriate.

Assignment 15: Much or many?

1. How ___ chairs do we need? (much / many)

2. How ___ sugar should I add? (much / many)

3. Correct this sentence: “There are much people in the room.”

4. Write one sentence using much and another using many.

16. Confusing Say, Tell, Speak, and Talk

The verbs say, tell, speak, and talk all relate to communication, but they are not used in exactly the same way. Say focuses on the words or message expressed. For example, “She said that she was tired.” If you mention the listener, you usually use say something to someone: “She said hello to me.”

Tell commonly takes a person as its object. We say “He told me the truth” and “The teacher told us to be quiet.” A common mistake is “She said me the answer.” The standard form is “She told me the answer” or “She said the answer to me.”

Speak is often used for languages, formal situations, and the act of communicating verbally. For example, “He speaks Spanish” and “May I speak to the manager?” Talk is common in everyday conversation and often emphasises a discussion between people: “We talked about our plans.”

These verbs sometimes overlap. For example, both “We spoke about the problem” and “We talked about the problem” are correct. The important thing is to learn their common grammatical patterns rather than assume they can always replace one another.

Assignment 16: Choose the correct verb

1. She ___ me that the office was closed. (said / told)

2. He ___ three languages. (speaks / tells)

3. Correct this sentence: “My father said me to wait.”

4. Complete the sentence: “We talked ___ the examination.” (about / to)

5. Write a sentence using say and another using tell.

17. Confusing Make and Do

The verbs make and do are both common, but they are used in different expressions. Make often refers to creating, producing, preparing, or causing something. Examples include “make a cake,” “make a decision,” and “make a mistake.” In these expressions, the verb focuses on producing a result or bringing something about.

Do often refers to performing an activity, task, or piece of work. Examples include “do homework,” “do the laundry,” and “do your best.” These combinations are established expressions, so choosing between make and do often requires learning the phrase as a whole.

The distinction is not always obvious from the meaning of the noun. For example, we say “make progress” but “do research” in many common contexts. Although both expressions describe activities or results, English convention determines which verb is normally used.

A useful learning method is to record common verb-noun combinations together. Instead of memorising decision alone, learn make a decision. Instead of memorising homework, learn do homework. Practising complete phrases helps you use them more accurately in conversation and writing.

Assignment 17: Make or do?

1. Please ___ your homework before dinner. (make / do)

2. We need to ___ a decision today. (make / do)

3. Correct this sentence: “I did a serious mistake.”

4. Complete the expression: “___ your best.” (Make / Do)

5. Write one sentence with make and another with do.

18. Confusing Since and For

Since and for are often used when describing how long a situation has continued. Since identifies the starting point of a period, while for identifies the duration. For example, “I have lived here since 2020” gives the starting year, while “I have lived here for six years” gives the length of time.

These expressions commonly appear with the present perfect when a situation began in the past and continues into the present. For example, “She has worked at the school for three years” suggests that she started working there three years ago and still works there. The present perfect continuous is also possible with many ongoing activities: “She has been studying since morning.”

Use since with a point in time, such as Monday, last year, 8 a.m., or I was a child. Use for with a duration, such as two hours, five days, or several years. The distinction is about the information provided, not the length of the period.

Both words can occur with other tenses and meanings, so they should not be treated as exclusive markers of the present perfect. For example, “I waited for two hours” uses the past simple because the waiting period is presented as completed. The key is to match the tense to the intended time relationship.

Assignment 18: Since or for?

1. I have known her ___ 2018. (since / for)

2. We have been waiting ___ thirty minutes. (since / for)

3. Correct this sentence: “He has studied English since three months.”

4. Write one sentence using since and another using for.

19. Using Double Negatives in Standard English

A negative sentence expresses that something is not true, does not happen, or is absent. In standard formal English, a single negative construction is generally used to express a single negative meaning. For example, “I don’t know anything about it” is standard, while “I don’t know nothing about it” is generally considered nonstandard in formal written English when the intended meaning is that the speaker knows nothing.

This is because don’t already makes the sentence negative, and nothing is also negative in its usual use. Standard English normally uses anything in this type of negative sentence: “I don’t have anything to add.” Similarly, “She didn’t see anybody” is the standard form rather than “She didn’t see nobody.”

However, it is important to understand that some dialects of English use negative concord, a systematic grammatical pattern in which multiple negative words express one negative meaning. Such patterns are part of the grammar of those dialects and should not be confused with random mistakes. In formal Standard English writing, learners are usually expected to follow the single-negative patterns taught here.

Positive sentences also use anything and anybody differently from negative sentences. For example, “You can ask me anything” means there is no restriction on what you may ask. In “I don’t need anything,” the word anything appears within a negative construction.

Assignment 19: Correct the sentences

1. Rewrite in standard formal English: “I don’t want nothing.”

2. Correct this sentence: “She didn’t tell nobody.”

3. Complete the sentence: “I haven’t seen ___ unusual.” (anything / nothing)

4. In one sentence, explain why some speakers may use double negatives systematically in their dialect.

20. Confusing Fewer and Less

Fewer is generally used with plural countable nouns, while less is generally used with uncountable nouns. For example, “There are fewer students today” refers to a smaller number of individual students. “We have less time today” refers to a smaller amount of time.

The difference is based on how the noun is being used. We normally say fewer books, fewer mistakes, and fewer visitors because these items can be counted. We normally say less water, less money, and less information because these nouns are uncountable in their usual meanings.

There are established exceptions and special conventions. Less than ten minutes is standard because time is uncountable in that expression. In some contexts, less is also used with amounts, measurements, money, distance, or time, even when a numerical quantity is involved. For beginners, the countable-versus-uncountable distinction is a reliable starting point.

When revising a sentence, ask whether the noun refers to separate countable items or to an amount. If you can naturally count the items one by one, fewer is usually appropriate. If you are referring to a quantity or mass, less is usually the better choice.

Assignment 20: Fewer or less?

1. We need ___ chairs for the meeting. (fewer / less)

2. There is ___ milk in the bottle than I expected. (fewer / less)

3. Correct this sentence: “I made less spelling mistakes today.”

4. Write one sentence using fewer and another using less.

21. Confusing Gerunds and Infinitives

A gerund is the -ing form of a verb used as a noun or in a noun-like role. An infinitive is usually formed with to plus the base form of a verb, as in to read, to write, and to learn. Both forms can appear after verbs, but the correct choice often depends on the main verb.

Some verbs are commonly followed by a gerund. For example, we say “I enjoy reading,” “She avoids driving at night,” and “They finished preparing the report.” In these sentences, reading, driving, and preparing follow verbs that commonly take the gerund.

Other verbs are commonly followed by an infinitive. For example, “I want to learn,” “He decided to leave,” and “We hope to win.” Using the wrong form can make a sentence ungrammatical in standard usage, so it helps to learn which pattern normally follows each verb.

Some verbs can take either a gerund or an infinitive, sometimes with little change in meaning and sometimes with a change in meaning. For example, “I started reading” and “I started to read” are both correct. But “I stopped smoking” means I quit the habit, while “I stopped to smoke” means I paused another activity in order to smoke.

Assignment 21: Gerund or infinitive?

1. I enjoy ___ (to cook / cooking).

2. She plans ___ (to study / studying) medicine.

3. Correct this sentence: “He avoided to speak to the manager.”

4. Complete the sentence: “We hope ___ (to see / seeing) you soon.”

5. Write a sentence using enjoy and another using decide.

22. Using Although and But Together Incorrectly

Although and but can both introduce contrast, but they usually perform different grammatical roles. Although introduces a dependent clause, while but connects contrasting words, phrases, or clauses. Understanding this distinction helps you avoid combining two structures unnecessarily.

For example, “Although it was raining, we continued playing” is correct. The clause beginning with although depends on the main clause to complete the thought. You can also write “It was raining, but we continued playing.” In this version, but joins two contrasting independent clauses.

In standard edited English, “Although it was raining, but we continued playing” is generally considered incorrect because both words are being used to mark the same contrast in one construction. Choose either the although pattern or the but pattern.

The same principle applies to other conjunctions. For example, use “Because I was tired, I went to bed early” or “I was tired, so I went to bed early.” Avoid combining because and so unnecessarily in a construction where both attempt to connect the same cause and result.

Assignment 22: Correct the conjunctions

1. Correct this sentence: “Although she was ill, but she attended class.”

2. Rewrite this sentence using but: “Although it was expensive, I bought it.”

3. Correct this sentence: “Because the road was blocked, so we took another route.”

4. Write one correct sentence with although and another with but.

23. Making Incorrect Plurals

Plural nouns refer to more than one person, animal, place, or thing. Many English nouns form their plurals by adding -s or -es, but some follow different spelling patterns. Learners sometimes apply a regular plural ending to an irregular noun or add a plural ending to a noun that is already plural.

For regular nouns, add -s to many words, as in book/books and chair/chairs. Nouns ending in sounds or letters that require -es often form plurals such as bus/buses, box/boxes, and watch/watches. Nouns ending in a consonant followed by y commonly change the y to ies, as in city/cities. When a vowel comes before the y, the usual pattern is to add -s, as in boy/boys.

Irregular plurals must often be learned individually. Examples include child/children, man/men, woman/women, tooth/teeth, and foot/feet. Some nouns, such as sheep, have the same form in both singular and plural uses. These differences are part of standard English usage and cannot always be predicted from a single spelling rule.

Some nouns that end in -s are already plural or are treated as plural in ordinary use, such as scissors and trousers. We commonly say “a pair of scissors” or “two pairs of scissors.” Other nouns, such as news, end in -s but take a singular verb: “The news is surprising.” Therefore, the final letter alone does not determine whether a noun is singular or plural.

Assignment 23: Correct the plural forms

1. Write the plural of tooth.

2. Correct this phrase: “Four childs.”

3. Complete the sentence: “The ___ (box) are on the shelf.”

4. Correct this sentence: “The news are encouraging.”

5. Write a sentence using an irregular plural noun.

24. Confusing Who and Whom

Who and whom both refer to people, but their grammatical roles differ in formal Standard English. Use who when the word functions as the subject of a clause, meaning the person performs the action. For example, “Who called you?” uses who as the subject of called.

Use whom when the word functions as an object, particularly in formal writing and after prepositions. For example, “Whom did you invite?” uses whom as the object of invite. Similarly, “To whom should I send the email?” uses whom after the preposition to.

A practical way to decide is to replace the question word with he or him, or she or her. If the answer would use he or she, who is appropriate. If it would use him or her, whom is appropriate. For example, “Who called?” can be answered with “He called,” while “Whom did you call?” can be answered with “I called him.”

In everyday conversation, many speakers use who instead of whom, even in positions where formal grammar traditionally prefers whom. This is common in contemporary English. Learners should recognise both patterns, while understanding that whom may be expected in formal writing and certain fixed expressions.

Assignment 24: Who or whom?

1. ___ sent you this message? (Who / Whom)

2. ___ did the manager select for the position? (Who / Whom)

3. Complete the formal expression: “To ___ it may concern.”

4. Explain why who is correct in “Who opened the door?”

5. Write one question using who and one using whom.

25. Writing Sentence Fragments and Run-On Sentences

A complete sentence normally expresses a complete thought and contains an independent clause. An independent clause has a subject and a verb and can stand alone as a sentence. For example, “The students completed the assignment” is complete because it communicates a full idea.

A sentence fragment is a word group presented as a complete sentence even though it does not express a complete thought in that context. For example, “Because the students were tired” leaves the reader waiting for what happened. A complete version is “Because the students were tired, the teacher ended the lesson early.” The dependent clause now connects to a main clause.

A run-on sentence occurs when two or more independent clauses are joined without the appropriate punctuation or connecting word. For example, “I finished my work I went home” contains two complete clauses without a suitable connection. You can correct it by separating the clauses into two sentences or joining them with appropriate punctuation and a conjunction.

A comma splice is a particular type of run-on sentence in which two independent clauses are joined using only a comma. For example, “The meeting ended, we went to lunch” is a comma splice. A corrected version is “The meeting ended, and we went to lunch.” You could also write “The meeting ended. We went to lunch.”

Not every long sentence is a run-on, and not every short fragment is wrong in every context. Fragments can be used deliberately in informal writing, advertising, or creative work. However, in standard academic and professional writing, complete sentences and clear connections between clauses are generally expected.

Assignment 25: Correct sentence structure

Instructions: Rewrite each item as a complete, correctly punctuated sentence.

1. Correct this fragment: “Although the weather was bad.”

2. Correct this run-on sentence: “I called my friend she did not answer.”

3. Correct this comma splice: “The lesson ended, the students left.”

4. Choose the complete sentence:

   • A. When we arrived at the station.

   • B. We waited at the station until the train arrived.

5. Write one complete sentence that contains a dependent clause and a main clause.

Answer Key with Explanations

Complete the assignments before checking this section. The explanations show not only which answers are correct but also why the grammar rules apply. For open-ended questions, the answers provided are examples, and other grammatically correct answers are possible.

Assignment 1: Subject-verb agreement

1. Studies. My sister is a third-person singular subject, so the present simple verb takes -s.

2. Were. Children is plural, so the past-tense form of be is were.

3. Needs. Everyone is grammatically singular in standard English.

4. The manager of the offices is absent. The subject is manager, not offices.

5. Enjoy. The compound subject my friends and I is plural.

Assignment 2: Verb tenses

1. Drives. The present simple describes a routine.

2. Am talking. The present continuous describes an activity happening now.

3. Arrived. Yesterday refers to a completed past time.

4. She completed the course last month. The past simple is appropriate with last month.

5. Sample answers: I read every evening. / I am reading now. The first describes a habit, and the second describes an ongoing activity.

Assignment 3: Do, does, and did

1. He doesn’t understand the question. The main verb stays in its base form after doesn’t.

2. Eat. In “Did you eat breakfast?”, did carries the past tense.

3. Does your brother play tennis? Use the base form play after does.

4. Receive. The correct sentence is “We did not receive your email.”

Assignment 4: The verb be

1. Am. Use am with I.

2. Were. Use were with the plural subject students.

3. My parents are at home. The plural subject takes are.

4. She understands the lesson. Understand is the main verb, so is is unnecessary here.

5. Was. The subject he takes was in the past continuous.

Assignment 5: Articles

1. An. Engineer begins with a vowel sound.

2. A. European begins with a /y/ sound.

3. Please give me some information. Information is normally uncountable.

4. The. The second sentence refers to the man already introduced.

5. Sample answer: I bought a phone. The phone has a large screen. The first sentence introduces the phone, while the second identifies it.

Assignment 6: Countable and uncountable nouns

1. Much. Information is uncountable.

2. I bought two loaves of bread. Loaves counts the units of bread.

3. Sheets. A sheet is a countable unit of paper.

4. B. She gave me a piece of advice. This is a standard way to count a piece of information expressed as advice.

5. Sample answers: The furniture is new. / The chairs are new. Furniture is uncountable, while chairs is plural and countable.

Assignment 7: Prepositions

1. In. Use in with months.

2. At. Use at with specific clock times.

3. In. The usual expression is interested in.

4. I listened to the teacher carefully. The verb listen normally takes to before its object.

5. For. Five years is a duration. Use since with a starting point.

Assignment 8: Pronouns

1. I. The pronoun is part of the subject.

2. Them. The pronoun receives the action of congratulated.

3. Our. The possessive determiner comes before the noun classroom.

4. The principal invited my friend and me. The pronoun is the object of invited.

5. Sample answers: They arrived early. / The teacher welcomed them. They is the subject, while them is the object.

Assignment 9: Your and you’re

1. You’re. The sentence means “You are invited to the meeting.”

2. Your. The word shows whose notebook is meant.

3. You’re doing a great job. You’re means you are.

4. Sample answers: Your bag is on the chair. / You’re very helpful.

Assignment 10: There, their, and they’re

1. They’re. The sentence means “They are going to arrive soon.”

2. Their. It shows that the lunch boxes belong to the children.

3. There are two emails for you. There are introduces the existence of two emails.

4. Sample answers: Put the bag there. / Their house is nearby. / They’re waiting outside.

Assignment 11: Its and it’s

1. It’s. The sentence means “It is a beautiful morning.”

2. Its. It shows that the wings belong to the bird.

3. It’s been a long day. Here, it’s means it has.

4. Sample answers: The company changed its name. / It’s time to leave.

Assignment 12: Adjectives and adverbs

1. Correctly. The adverb describes how the student answered.

2. Confident. The adjective describes the noun speaker.

3. He speaks English fluently. The adverb fluently describes how he speaks.

4. A. The soup smells delicious. The linking verb smells connects the subject to the adjective delicious.

5. Sample answers: She is a careful driver. / She drives carefully. The adjective describes the driver, while the adverb describes the action.

Assignment 13: Comparatives and superlatives

1. Lighter. This is the standard comparative form.

2. He is the strongest player. Do not combine most with strongest.

3. Best. Best is the superlative form of good.

4. Sample answers: My room is larger than yours. / This is the largest room in the house.

Assignment 14: Questions

1. Is she at home? Move is before the subject.

2. Where do they live? Use do to form the present simple question.

3. A. Did you finish the work? The main verb remains in its base form after did.

4. Sample answer: Why did you arrive late? The helping verb comes before the subject.

5. Sample answer: Who opened the door? Who is the subject performing the action.

Assignment 15: Much and many

1. Many. Chairs is a plural countable noun.

2. Much. Sugar is uncountable.

3. There are many people in the room. People is plural and countable.

4. Sample answers: We don’t have much time. / Many students attended the lecture.

Assignment 16: Say, tell, speak, and talk

1. Told. Tell commonly takes a person as its object: “She told me.”

2. Speaks. Speak is used when describing the languages someone can use.

3. My father told me to wait. The pattern is tell someone to do something.

4. About. The usual expression is talk about something.

5. Sample answers: She said that she was busy. / She told me that she was busy. The second sentence identifies the listener directly after told.

Assignment 17: Make and do

1. Do. The standard expression is do your homework.

2. Make. The standard expression is make a decision.

3. I made a serious mistake. The usual expression is make a mistake.

4. Do. The expression is do your best.

5. Sample answers: I made a cake. / I did the laundry.

Assignment 18: Since and for

1. Since. The year 2018 is a starting point.

2. For. Thirty minutes is a duration.

3. He has studied English for three months. Use for with a duration.

4. Sample answers: I have lived here since 2022. / I have lived here for four years.

Assignment 19: Double negatives

1. I don’t want anything. This is the standard formal English construction.

2. She didn’t tell anybody. Use anybody in this negative sentence.

3. Anything. The correct sentence is “I haven’t seen anything unusual.”

4. Sample answer: Some dialects use negative concord, in which multiple negative words express one negative meaning. Such patterns are systematic features of those dialects, although formal Standard English generally uses the patterns practised in this section.

Assignment 20: Fewer and less

1. Fewer. Chairs are countable.

2. Less. Milk is uncountable.

3. I made fewer spelling mistakes today. Mistakes is a plural countable noun.

4. Sample answers: We received fewer applications this week. / We have less time to prepare.

Assignment 21: Gerunds and infinitives

1. Cooking. Enjoy is normally followed by a gerund.

2. To study. Plan is normally followed by an infinitive.

3. He avoided speaking to the manager. Avoid is followed by a gerund.

4. To see. The usual expression is hope to see.

5. Sample answers: I enjoy reading. / She decided to leave early.

Assignment 22: Although and but

1. Although she was ill, she attended class. Remove but from the same contrast construction.

2. It was expensive, but I bought it. But joins the contrasting ideas.

3. Because the road was blocked, we took another route. Remove so from this construction.

4. Sample answers: Although it was raining, we went outside. / It was raining, but we went outside.

Assignment 23: Plural forms

1. Teeth. This is the irregular plural of tooth.

2. Four children. The plural of child is children.

3. Boxes. The plural of box is formed by adding -es.

4. The news is encouraging. News takes a singular verb in standard English.

5. Sample answer: The children played outside. Children is an irregular plural noun.

Assignment 24: Who and whom

1. Who. The person performs the action of sending.

2. Whom in formal usage, although who is common in everyday speech. The person receives the action of selected.

3. Whom. “To whom it may concern” is a conventional formal expression.

4. Who is correct because the person performs the action of opening the door. You can answer, “He opened the door.”

5. Sample answers: Who called you? / Whom did you invite? The second uses whom as the object in formal usage.

Assignment 25: Sentence structure

1. Although the weather was bad, we continued the journey. The dependent clause is completed by a main clause.

2. I called my friend, but she did not answer. The clauses are joined with a conjunction and appropriate punctuation.

3. The lesson ended, and the students left. The conjunction joins the independent clauses.

4. B. We waited at the station until the train arrived. This sentence expresses a complete thought.

5. Sample answer: When the rain stopped, the children went outside. The first clause depends on the main clause, which completes the sentence.

Conclusion

Correcting common English grammar mistakes begins with understanding how words and sentences work together. Subject-verb agreement, verb tenses, articles, prepositions, pronouns, and sentence structure may seem challenging at first, but each becomes easier when you learn the principle behind it and practise applying it.

Remember the key distinctions covered in this article. Use doesn’t with the base form of a verb, choose a or an according to the following sound, distinguish countable nouns from uncountable nouns, and use prepositions in their established expressions. Also, check whether a sentence needs a subject, a helping verb, or a clearer connection between its clauses.

Grammar learning is an ongoing process, and mistakes are a normal part of that process. Rather than trying to memorise all 25 corrections at once, focus on a few at a time. Write your own examples, use the rules in conversations and professional writing, and review sentences that you find difficult.

A useful daily exercise is to write five sentences about your activities, then check their verb forms, articles, pronouns, prepositions, and punctuation. Keep a record of repeated errors and rewrite each incorrect sentence correctly. Over time, this habit can help you recognise mistakes more quickly and express your ideas with greater accuracy and confidence.