Grammar Rules in English

Grammar is 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:

  1. Subject/Verb Agreement
  2. Nouns and Pronouns
  3. Verbs and Verb Forms

1. 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:

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

  2. 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.

  3. 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.

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

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

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

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

  8. 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.

  9. 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.

2. 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.

Subject pronouns (renames nouns in subject position)

  • Singular
    • 1st person: I
    • 2nd person: you
    • 3rd person:
      • Masculine (names males): he
      • Feminine (names females): she
      • Neuter (names nouns without gender): it
  • Plural
    • 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.

  • Singular
    • 1st person: my
    • 2nd person: your
    • 3rd person:
      • Masculine: his
      • Feminine: her
      • Neuter: its
  • Plural
    • 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.

  • Singular
    • 1st person: mine
    • 2nd person: yours
    • 3rd person:
      • Masculine: his
      • Feminine: hers
      • Neuter does not exist.
  • Plural
    • 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.

  • Singular
    • 1st person: me
    • 2nd person: you
    • 3rd person:
      • Masculine: him
      • Feminine: her
      • Neuter: it
  • Plural
    • 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.

  • Singular
    • 1st person: myself
    • 2nd person: yourself
    • 3rd person:
      • Masculine: himself
      • Feminine: herself
      • Neuter: itself
  • Plural
    • 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:

  • Everyone gather around the campfire!
  • There will be a prize for each of the children.
  • 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.

3. Verbs and Verb Forms

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

  1. Simple Present: write
  2. Simple Past: wrote
  3. Present Participle: writing
  4. 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.