ACT English Test Prep: Grammar Rules

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Grammar Rules

Grammar: The study and application of combining words to form sentences.

A well-formed sentence contains a subject and a verb and expresses a complete thought. The ACT English Test includes questions that will test your ability to identify and correct poorly written sentences. You should have a firm grasp of the following concepts:

Subject/Verb Agreement

Nouns and Pronouns

Verbs and Verb Forms

Subject/Verb Agreement

A sentence has two essential parts: a subject and a verb. The subject is who or what the sentence is about. The verb tells you what the subject is doing, what is being done to the subject, or something about the state of being of the subject. The subject and verb must agree; that is, they must share the same person, number, and voice. In addition, verbs in successive clauses and sentences normally must match in voice and tense.


A verb must have the same person as the subject.

1st person: I am eating lunch.

2nd person: You are eating lunch.

3rd person: She is eating lunch.

In addition to person, subject and verb must agree in number, which is either singular or plural.


1st person, singular: I have a headache today.

2nd person, singular: You are my best friend in the entire world!

3rd person, singular: It/He/She was interesting today.

1st person, plural: We make amazing barbecue.

2nd person, plural: You are going to work in pairs for this assignment.

3rd person, plural: They enjoy suspense novels.


Active voice means that the subject is acting. In the following sentence, dog is the subject.

The dog licked my brother.

The ACT English Test is more likely to reward answer choices that are in the active voice. The graders on the Writing Test are also more likely to award points to essays that are in the active voice.

Passive voice means that the subject is being acted upon. In the following sentence, my brother is the subject.

My brother was licked by the dog.

Although some situations demand the passive voice, the vast majority of passive sentences can be effectively reworded to have active voice.


Verb tense provides you with information about when the action took place. Actions take place in the present, in the past, or in the future. The ACT English Test will not require you to recall the names of the tenses, but it will require you to recognize correct and incorrect uses of verb tense. While there are many classifications of verb tense, for the purpose of preparing for the ACT, you should remember the following tenses:

Simple past—the action took place in the past and is completed: Jenny worked a double shift at the mall yesterday.

Past progressive—the action was taking place in the past when some other action took place: Jenny was working at the mall last night when the fire alarm sounded.

Past perfect—the action took place before another specified point in time or action in the past: Jenny had worked at the mall before she went to college.

Simple present—the action takes place regularly or repeatedly: Jenny works at the mall after school. (She works there repeatedly.)

Present progressive—the action is taking place now: Jenny is working at the mall until 9 o’clock tonight.

Present perfect—the action began in the past and is ongoing: Jenny has worked at the mall for the last two years.

Future—the action will take place in the future: Jenny will work more hours at the mall next summer.

Future progressive—the action will be taking place in the future when some other action will take place: Jenny will be working at the mall when her friends begin gathering for her surprise party.

Future perfect—the action took place before another specified action or point in time in the future: Jenny will have worked over 3 years at the mall when she graduates next spring.

Some special verb tenses:

Habitual actions in the past using would and used to—the action took place on a regular basis in the past:

When I was a boy, I would buy a root beer float every chance I could. OR When I was a boy, I used to buy a root beer float every chance I could.

Near future with progressive tenses of go—the action is upcoming relative to past or present:

I was going to call you, but I could not find my phone.

The girls are going to have dinner before the movie tonight.

Nouns and Pronouns

The English language contains two forms of nouns: proper nouns, which name a specific person, place, or object, and common nouns, which name a nonspecific person, place, or object. Proper nouns begin with an uppercase letter, and common nouns do not. Pronouns take the place of either a proper or a common noun. Generally, a pronoun begins with an uppercase letter only if the pronoun begins a sentence. The one notable exception is the personal pronoun I, which is always capitalized. A pronoun should be placed so that it clearly refers to a specific noun. One of the errors that the ACT commonly tests is a pronoun with an unclear antecedent. You should be able to select pronouns from the appropriate set, as follows:

Personal Pronouns

Personal pronouns come in several forms, including subject pronouns, possessive determiners, possessive pronouns, object pronouns, and reflexive pronouns. Each of these pronouns is discussed next.

Subject pronouns (renames nouns in subject position)


1st person: I

2nd person: you

3rd person:

Masculine (names males): he

Feminine (names females): she

Neuter (names nouns without gender): it


1st person: we

2nd person: you

3rd person: they

Consider the following example:

Mandy (singular, 3rd person, feminine) recently graduated from college;

she (singular, 3rd person, feminine) now has a degree in nursing.

Possessive determiners (assigns possession)

These can also be called possessive adjectives.


1st person: my

2nd person: your

3rd person:

Masculine: his

Feminine: her

Neuter: its


1st person: our

2nd person: your

3rd person: their

Consider the following example:

That piece of paper is my boarding pass. (The boarding pass belongs to the speaker, who is singular and 1st person.)

Possessive pronouns (replace nouns and show possession)

These do not mark nouns, as the possessive determiners do; rather, they replace nouns.


1st person: mine

2nd person: yours

3rd person:

Masculine: his

Feminine: hers

Neuter does not exist.


1st person: ours

2nd person: yours

3rd person: theirs

Take note that no apostrophes are used in these pronouns, even though they indicate possession.

Consider the following example:

That boarding pass is hers. (The boarding pass belongs to a singular, 3rd person, female.)

Object pronouns (rename nouns in object position)

These are used as indirect and direct objects in verb phrases and as objects of prepositions.


1st person: me

2nd person: you

3rd person:

Masculine: him

Feminine: her

Neuter: it


1st person: us

2nd person: you

3rd person: them

Consider the following example:

John (singular, 3rd person, masculine) wondered why everyone kept staring at him (singular, 3rd person, masculine) during dinner. (The pronoun is the object of the preposition at.)

Reflexive pronouns (rename the subject in object position)

These are used when the subject is also the object of the verb.


1st person: myself

2nd person: yourself

3rd person:

Masculine: himself

Feminine: herself

Neuter: itself


1st person: ourselves

2nd person: yourselves

3rd person: themselves

Consider the following example:

If we (plural, 1st person) don’t win this game, boys, we’ll be kicking ourselves (plural, 1st person) tomorrow. (The subject group of boys represented by we is kicking the same group of boys.)

In addition, the ACT requires that you distinguish among the preceding personal pronouns, as well as relative and indefinite pronouns.

Common traps with personal pronouns

Following is a description of some common mistakes of pronoun use. Be especially cautious of these traps on the ACT.

Use subject pronouns in compound subjects (subjects with more than one noun)

Paul, you, and I will be Team A.

NOT: Paul, you, and me...

She and Mark have been dating for years.

NOT: Mark and her...

Use subject pronouns as subjects of clauses in comparative constructions (more.. .than, less.. .than, as.. .as, etc.) when the clause is not repeated. Add the missing clause back to reveal the subject position of the pronoun.

No one in the classroom was as surprised as I (was).

NOT: . . . as me.

He worked longer today than she (worked).

NOT: . . . than her.

Use possessive determiners before gerunds (-ing verb forms)

Her singing has often been admired.

The class was shocked by his studying for the exam.

Relative Pronouns

These are used to identify nouns at the beginning of relative clauses.


Non-human: which/that

Bob loves dogs that can catch Frisbees. (Dogs can catch Frisbees.)

Human: who

Jenny is looking for a mechanic who has experience with carburetors. (Some mechanic has experience with carburetors.)


Non-human: which/that

I finally got back the DVD that John borrowed. (John borrowed the DVD.)

Human: whom

Traci has not yet been paid by the client whom she billed last week. (Traci billed the client.)


Non-human or human: whose

Mrs. Peters loves Edgar Allan Poe, whose poems and stories give her chills. (Edgar Allan Poe’s poems and stories give her chills.)

Indefinite Pronouns

Indefinite pronouns are used to represent an indefinite number of persons, places, or things. Following are some examples of indefinite pronouns:

1. Everyone gather around the campfire!

2. There will be a prize for each of the children.

3. One of my sisters always volunteers to drive me to school.

Be sure to maintain consistency in pronoun person and number.

It is not grammatically correct to use the plural pronoun their to represent neutral gender with singular nouns. This is an example of a major difference between standard written English and the English that we ordinarily use when speaking.

A small child should always be with his or her parent or guardian.

NOT—A small child should always be with their parent or guardian.

Verbs and Verb Forms

A verb describes the action that is taking place in the sentence. All verbs have four principle forms:

Simple Present: write

Simple Past: wrote

Present Participle: writing

Past Participle: written

Simple Past vs. Past Participle

The simple past and past participle forms of verbs can sometimes be confusing. Most past tenses are formed by adding -ed to the word.

Simple Present Tense—We move often.

Simple Past Tense—We moved again this year.

Some verbs have irregular past tense forms.

Simple Present Tense—I see my best friend every day.

Simple Past Tense—I saw my best friend yesterday.

Simple Present Tense—My little sister eats her breakfast quickly.

Simple Past Tense—My little sister ate her breakfast quickly.

Remember that the perfect tenses include a form of have, a so-called auxiliary verb, and a past participle.

Past Participle—I had seen my best friend the day before.

NOT—I had saw my best friend the day before.

Past Participle—My little sister has eaten her breakfast quickly.

NOT—My little sister has ate her breakfast quickly.

In most cases, be sure to maintain parallel verb forms throughout a sentence.

We rode to school on the bus and started our first class at 9:00 a.m.

NOT—We ride to school on the bus and started our first class at 9:00 a.m.

His brother walks to school and often arrives ahead of us.

NOT—His brother walks to school and often arrived ahead of us.

Some sentences follow a specific sequence of tenses. The order of the clauses is normally interchangeable.

Hypothetical/Conditional: These sentences usually use a clause with if and a subjunctive verb phrase (were to walk, for example) in one clause, and a conditional (would) verb construction in the second clause.

If I were to buy tickets for the game, would you go with me?

Mike would be shocked if he were to discover the truth.

If I were you, I’d get out of town as fast as you can. (Notice the contraction I’d from I would.)

Simple past/past progressive

The accident occurred while the traffic light was changing.

Simple past/past perfect

The children had drunk all their milk before Ms. Thompson dismissed them for recess.

Simple past/simple present

In a recent poll, 7% of teens thought that Vietnam is in North America.

Simple present/future progressive

I will be cleaning the house when you return from work.

Simple present/future perfect

By the time you awaken, Dr. Smythe will have finished stitching the incision.

Simple present/present progressive (suggests the future)

I am watching a movie when John leaves the living room.

Simple present/present perfect

Martha knows that she has earned all of her promotions.

Future/simple past

Susie will cry if you lost her teddy bear.

Future/simple present

I will buy you both lunch if you wash my car.

Future/present perfect

Sammy’s Pizza will close this week if quarterly profits have not improved.

Future perfect/present perfect (equivalent to future perfect/simple present)

Our cows will have moved toward the barn by the time the bobcat has entered the pasture.

Sentence Structure Rules

Sentence Structure: The grammatical arrangement of words and phrases in sentences.

It is important that a sentence be arranged so that the idea is expressed completely and clearly. The ACT will test your ability to recognize and correct errors involving the following:

Run-on Sentences

Sentence Fragments

Misplaced Modifiers


Run-on Sentences

A run-on sentence is a sentence that is composed of more than one main idea and that does not use proper punctuation or connectors. The ACT requires you to recognize run-on sentences, as well as avoid creating run-on sentences. The following are examples of run-on sentences along with suggested corrections:

Run-on Sentence—Jill is an actress she often appears in major network television shows.

Correct Sentence—Jill is an actress who often appears in major network television shows.

Run-on Sentence—My nephew loves to play football you can find him on the practice field almost every day.

Correct Sentences—My nephew loves to play football. You can find him on the practice field almost every day.

Run-on sentences are often created by substituting a comma for a semicolon or a period. This is called a comma splice, and it is incorrect. Following are examples of comma splices along with suggested corrections:

Comma Splice—Yesterday my mother prepared my favorite dinner, she even baked a cake.

Correct Sentence—Yesterday my mother prepared my favorite dinner; she even baked a cake.

Comma Splice—History is my favorite subject in school, I always get the highest grade.

Correct Sentences—History is my favorite subject in school. I always get the highest grade.

Sentence Fragments

A sentence fragment is a dependent clause, which must function as part of a complete sentence and cannot stand alone. (Fragments often lack a subject or a verb with tense. Sentence fragments are incorrectly punctuated as if they were complete sentences.) The following are examples of sentence fragments along with suggested corrections:

Sentence Fragment—My car is difficult to start in the winter. Because of the cold weather.

Correct Sentence—Because of the cold weather, my car is difficult to start in the winter.

Sentence Fragment—Michigan State University offers a variety of courses. Such as Psychology, Biology, Physics, and Music.

Correct Sentence—Michigan State University offers a variety of courses, such as Psychology, Biology, Physics, and Music.

Misplaced Modifiers

Modifiers are words, phrases, or clauses that provide description in sentences. Typically, a modifier is placed near the word or phrase that it modifies. A misplaced modifier creates confusion because it appears to modify some word or phrase other than the word or phrase it was intended to modify. The following are examples of misplaced modifiers along with suggested corrections:

1. Misplaced Modifier—Josh had trouble deciding which college to attend at first. (Does he plan to attend more than one college?)

2. Correct Sentence—At first, Josh had trouble deciding which college to attend.

3. Misplaced Modifier—The young girl was walking her dog in a raincoat. (Was her dog in a raincoat?)

4. Correct Sentence—The young girl in a raincoat was walking her dog.


Parallelism, or parallel construction, enables you to show order and clarity in a sentence or a paragraph by putting grammatical elements that have the same function in the same form. For example, when two adjectives modify the same noun, the adjectives should have similar forms. When providing a list, each element of the list should have the same form. Also, when the first half of a sentence has a certain structure, the second half should maintain that structure. Following are examples of faulty parallel construction along with suggested corrections:

1. Faulty Parallel Construction—Amy enjoyed running and to ride horses.

2. Correct Sentence—Amy enjoyed running and horseback riding.

3. Faulty Parallel Construction—Our field trip included a visit to the art museum, talking to a local artist, and a workshop on oil-painting techniques.

4. Correct Sentence—Our field trip included visiting the art museum, talking to a local artist, and attending a workshop on oil-painting techniques.


There are certain words and phrases in the English language that are often misused and that often show up on the ACT English Test. We’ve included a list of commonly misused words here, along with definitions and examples of the proper use of the words.

Accept, Except

Accept is a verb that means “to agree to receive something.”

Example: Jenny did not accept my invitation to dinner.

Except is usually a preposition that means “excluding,” or more rarely a verb meaning “to omit or leave out.”

Example: The entire family except for my sister Jill attended the reunion.

Affect, Effect

Affect is usually a verb meaning “to influence.”

Example: His opinion will affect my decision.

Effect is usually a noun meaning “result” or “force.”

Example: His opinion had a great effect on my decision.

All ready, Already

All ready means “completely ready” or “everyone is ready.”

Example: The instructor asked the climber if he was all ready to begin.

Already means “by or before a specified time.”

Example: The students were already late for the bus.

Among, Between

Among is used with more than two items.

Example: The scientist is living among a group of native people.

Between is used with two items.

Example: The race between Amy and Jenny was very close.

Amount, Number

Amount is used to denote a quantity of something that cannot be divided into separate units.

Example: There was a small amount of water in the glass.

Number is used when the objects involved are discrete or can be counted.

Example: A large number of students participated in the festivities.

Assure, Ensure, Insure

Assure means “to convince,” or “to guarantee” and usually takes a direct object.

Example: I assure you that I will not be late.

Ensure means “to make certain.”

Example: Ensure that the door is locked when you leave.

Insure means “to guard against loss.”

Example: Please insure this package for $100.

Bring, Take

Bring should be used in situations where something is being moved toward you.

Example: Please bring me the book.

Take should be used in situations where something is being moved away from you.

Example: Did you take my book with you when you left?

Capital, Capitol

Capital refers to “the official seat of government of a state or nation.”

Example: The capital of Michigan is Lansing.

Capital can also be used to mean “wealth or money.”

Example: He needed to raise investment capital to start his company.

Capital, when used as an adjective, means “foremost,” or “excellent.”

Example: “That is a capital idea,” Steve said.

Capitol refers to the “building where government meets, or when capitalized, refers to the building in which the U.S. Congress is housed.”

Example: Some members of the legislature have their offices in the capitol building downtown.

Compare to, Compare with

Compare to means “assert a likeness.”

Example: My grandmother often compares me to my mother.

Compare with means “analyze for similarities and differences.”

Example: The detective compared the photograph with the drawing.

Complement, Compliment

Complement is a noun or verb that implies “something that completes or adds to” something else.

Example: The dessert was a tasty complement to my meal.

Compliment is a noun or verb that implies “flattery or praise.”

Example: Pam appreciated Mike’s compliment on her high test scores.

Eager, Anxious

Eager implies “an intense desire” and usually has a positive connotation. Example: Carrie was eager to begin her new job.

Anxious indicates “worry or apprehension” and has a negative connotation.

Example: Fred waited anxiously for the plane to take off.

Farther, Further

Farther refers to distance.

Example: Matt traveled farther than all of the others.

Further indicates “additional degree, time, or quantity.”

Example: The airline representative told us to expect further delays.

Fewer, Less

Fewer refers to units or individuals.

Example: Fewer students went on the class trip this year.

Example: I weigh fewer pounds this year than I did last year.

Less refers to mass or bulk.

Example: There is less air in my bicycle’s front tire than in its rear tire.

Example: I weigh less this year than I did last year.

Imply, Infer

Imply means “to suggest.” The speaker or author “implies.”

Example: His pants and shirt colors imply that he is color blind.

Infer means “to deduce,” “to guess,” or “to conclude.” The listener or reader “infers.”

Example: He is not color blind, so we can infer that he simply has bad taste in clothes.

Its, It’s

The possessive form of it is its.

Example: The dog lost its collar.

The contraction of it is is it’s.

Example: It’s too bad that your dog ran away.

Lay, Lie

Lay means “to put” or “to place,” and takes a direct object.

Example: Please lay your scarf on the back of the chair.

Lie means “to recline, rest, or stay,” or “to take a position of rest.” This verb does not take a direct object.

Example: Carrie likes to lie down when she gets home from school.

Learn, Teach

Learn means to “gain knowledge.”

Example: I have always wanted to learn how to cook.

Teach means to “impart, or give knowledge.”

Example: My uncle agreed to teach me to cook.

Lend, Borrow

Lend means to “give or loan something” to someone else.

Example: Will you lend me your jacket for the evening?

Borrow means to “obtain or receive something temporarily” from someone else.

Example: May I borrow your jacket for the evening?

Precede, Proceed

Precede means “to go before.”

Example: Katie preceded Kahla as an intern at the law office.

Proceed means “to move forward.”

Example: Please proceed to the testing center in an orderly fashion.

Principal, Principle

Principal is a noun meaning “the head of a school or an organization.” Example: Mr. Smith is the principal of our high school.

Principal can also mean “a sum of money.”

Example: Only part of the payment will be applied to the principal amount of the loan.

Principal can also be used as an adjective to mean “first,” or “leading.”

Example: Betty’s principal concern was that Gary would be late.

Principle is a noun meaning “a basic truth or law.”

Example: We learned the principles of democracy in class today.

Set, Sit

The verb set takes a direct object, while the verb sit does not.

Example: Please set the glass down on the table.

Example: Please sit in the chair next to mine.

Than, Then

Than is a conjunction used in comparative constructions.

Example: Jill would rather eat fruit than eat chocolate.

Then is an adverb denoting time.

Example: First, I will go for a run, then I will do my homework.

That, Which

That is used to introduce an essential clause in a sentence. Commas are not normally used before the word that.

Example: This is the book that Jenny recommended I read.

Which is best used to introduce a clause containing nonessential and descriptive information. Commas are required before the word which.

Example: That book, which is old and tattered, is a favorite of mine.

There, Their, They’re

There indicates location.

Example: My car is parked over there.

Their is a possessive determiner.

Example: Their car is parked next to mine.

They’re is a contraction of they are.

Example: They’re afraid of getting a ticket if the car is not moved.

To, Too, Two

To is a preposition.

Example: Send the check to my office.

Too is an adverb, and means also, excessively, or prohibitively.

Example: It is important that you read the textbook, too.

Example: John has been too sick to work this week.

Example: That silk scarf is too expensive for me to buy right now.

Two is a number.

Example: There are only two tickets remaining for the game.

Your, You’re

Your is a possessive determiner.

Example: Your brother is going to be late for school.

You’re is a contraction of you are.

Example: You’re going to be late as well.

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