Mastering SAT and ACT: Complete grammar and punctuation rules - Part 2

Mastering SAT and ACT: Complete grammar and punctuation rules - Part 2
In case you haven’t read the first part yet, check it out at Part 1. In this blog, we’ll cover the remaining rules that are frequently tested. Each section in this blog provides clear explanations and examples to help you recognize common mistakes and choose the best answers with confidence.

11. Subject-Verb Agreement

A. Forming Verbs

• Singular 3rd-person verbs end in -s → it runs, she writes, he studies

• Plural 3rd-person verbs do not end in -s → they run, they write, they study

• The most common irregular verb is to be:\n

  • Singular: is (present), was (past)

  • Plural: are (present), were (past)

Tip: If you're unsure about the subject, check the beginning of the clause where the verb appears.

B. Compound Subjects (Noun + Noun) = Plural
A compound subject consists of two or more nouns connected by and, making it plural.
Incorrect: The rhythm and melody of the song creates a unique atmosphere.
Correct: The rhythm and melody of the song create a unique atmosphere.

C. Prepositional Phrases
Prepositional phrases (starting with of, to, by, from, for, about, with, in, on, at) are often placed between the subject and verb, distracting from disagreements.
Incorrect: The growth of urban areas have led to an increase in pollution.
Correct: The growth of urban areas has led to an increase in pollution.
Trap: The subject is growth (singular), not urban areas.

Watch out for compound subjects in prepositional phrases!
Incorrect: The lion and the cheetah in the African savanna is apex predators.
Correct: The lion and the cheetah in the African savanna are apex predators.

D. Non-Essential Clauses
Non-essential clauses (extra information set off by commas) can distract from errors.
Incorrect: The honeybee, which plays a crucial role in pollination, are declining in population.
Correct: The honeybee, which plays a crucial role in pollination, is declining in population.
Tip: Ignore non-essential clauses when checking subject-verb agreement.

E. "Each" and "Every" = Singular
Words like each and every always take a singular verb.
Incorrect: Each of the students in the debate club have a different speaking style.
Correct: Each of the students in the debate club has a different speaking style.

Other Subject-Verb Agreement Rules to Know:

• Collective nouns (e.g., group, team, government, board, audience) = singular
  Correct: The jury delivers its verdict.
  Incorrect: The jury deliver their verdict.

• "There is" vs. "There are"
  There is + singular noun → There is a book on the table.
  There are + plural noun → There are many books on the table.

• Verbs before subjects (rare but tricky)
  Incorrect: In the center of the stage stands the performers.
  Correct: In the center of the stage stand the performers.

12. Verb Tense

A. Tense Consistency
Always keep verb tense consistent with that of other verbs in the paragraph. Paragraphs in the present should stay in the present; paragraphs in the past should stay in the past.
Start by checking the tense of the verbs in the sentence in question, as well as the surrounding sentences (before/after). The underlined verb must match the others.
Incorrect: Author Jane Austen (1775-1817) wrote many famous novels. She is known for her keen observations of society and wit.
Correct: Author Jane Austen (1775-1817) wrote many famous novels. She was known for her keen observations of society and wit.
Important: Correct answers are usually in the simple past (was, did, found) or the present. Answers with more complex tenses (would have done, will have gone) are rarely correct.

B. Present Perfect – has / have + verb
Indicates an action that began in the past and continues into the present.
Tip-offs: for and since
Incorrect: The Great Wall of China stands for thousands of years.
Incorrect: The Great Wall of China stands since ancient times.
Correct: The Great Wall of China has stood for thousands of years.
Correct: The Great Wall of China has stood since ancient times.

C. Simple Past – one-word past form
Describes a completed past action.
Incorrect: Marie Curie has discovered radium in 1898.
Correct: Marie Curie discovered radium in 1898.
The sentence describes a completed action that occurred in the past—the discovery happened in 1898.

D. Past Perfect – had + verb
When a sentence describes two completed actions in the past, the past perfect can be used to describe the action that happened first.
Most of the time, either the simple past or the past perfect can be used:
• Before Alan Turing became famous, he studied / had studied mathematics extensively.
However, when the phrase by the time appears, the past perfect must be used.
Incorrect: By the time the Wright brothers built their first airplane, they experimented with gliders for years.
Correct: By the time the Wright brothers built their first airplane, they had experimented with gliders for years.

E. Passive Voice
In the passive voice, the subject and object are flipped so that x did y becomes y was done by x.
In many cases, this form results in wordy and awkward sentences and is often associated with incorrect answer choices.
Incorrect: Many people reject artificial intelligence because ethical concerns are had by them about its use.
Correct: Many people reject artificial intelligence because they have concerns about its use.
In some cases, the passive voice is necessary for grammatical correctness.
Incorrect: The landmark novel To Kill a Mockingbird describes a small town in Alabama that inhabited by a diverse community.
Correct: The landmark novel To Kill a Mockingbird describes a small town in Alabama that is inhabited by a diverse community.

F. TO vs. -ING
You may also be asked to choose between the infinitive (to + verb) and the gerund (-ing form). There is no strict rule—these questions must be answered by ear.
Incorrect: Scientists are trying understanding how black holes form.
Correct: Scientists are trying to understand how black holes form.

G. Tense vs. Subject-Verb Agreement
On standardized tests, subject-verb agreement questions often disguise themselves as verb tense questions. The answer choices may contain different tenses, but only one option will be correct in terms of number.
SAT Example:
The traditions of ancient civilizations owe much to the oral histories that ______ for centuries.
A) has existed
B) have existed
C) exists
D) is existing
Correct Answer: B) have existed
The subject is histories (plural), so the verb must also be plural (have existed).
ACT Example:
The beliefs of early astronomers were shaped by celestial observations that ______ over thousands of years.
A) NO CHANGE
B) have accumulated
C) accumulates
D) is accumulating
Correct Answer: B) have accumulated
The subject observations is plural, so the verb must also be plural (have accumulated).

13. Parallel Structure & Word Pairs

A. Lists (Three or More Items)
All items in a list must follow the same grammatical structure:
• Noun, noun, and noun
• -ING, -ING, and -ING
• Verb, verb, and verb
Incorrect: The research project involved collecting data, analyzing results, and to write a report.
Correct: The research project involved collecting data, analyzing results, and writing a report.
Incorrect: The university offers courses in biology, chemistry, and conducting physics experiments.
Correct: The university offers courses in biology, chemistry, and physics.

B. Two Items
Parallel structure must also be maintained when only two items are joined by and or but.
Tip: If the sentence uses an infinitive (to + verb), you do not need to repeat to before the second verb.
Incorrect: The professor advised students to review the material and preparing for the exam.
Correct: The professor advised students to review the material and prepare for the exam.

C. Word Pairs
Some word pairs must always appear together:
• (N)either…(n)or
• Not only…but (also)
• As…as
• More/less…than
Incorrect: Unlike a bus, a bicycle can be used either on roads and in parks.
Correct: Unlike a bus, a bicycle can be used either on roads or in parks.
When using these word pairs, ensure the elements after them are parallel.
Incorrect: The new policy was introduced not only to reduce costs but also because it improves efficiency.
Correct: The new policy was introduced not only to reduce costs but also to improve efficiency.

14. Dangling & Misplaced Modifiers

A. Dangling Modifiers
A dangling modifier occurs when a descriptive phrase at the beginning of a sentence does not clearly refer to the correct noun (subject). The noun being described must appear immediately after the modifier.
Incorrect: Discovered in the 18th century, scientists continue to study the fossils of ancient marine reptiles.
(Who was discovered in the 18th century? This sentence incorrectly suggests that scientists were discovered, rather than the fossils.)
Correct: Discovered in the 18th century, the fossils of ancient marine reptiles continue to be studied by scientists.

B. Misplaced Modifiers
A misplaced modifier occurs when a descriptive phrase is too far from the word it is meant to modify, leading to confusion.
Incorrect: The scientist published a groundbreaking study on climate change that examined rising temperatures over the past century.
(This sentence suggests that climate change, not the study, examined rising temperatures.)
Correct: The scientist published a groundbreaking study that examined rising temperatures over the past century on climate change.
(This version clarifies that the study, not climate change, examined temperatures.)
To fix dangling or misplaced modifiers, always ensure that the modifying phrase is positioned next to the noun it logically describes.

15. Faulty Comparisons

Comparisons must be made between equivalent items—people must be compared to people, and things must be compared to things.
On standardized tests like the SAT and ACT, comparisons may involve both singular and plural nouns.

A. Singular Comparisons
Incorrect: Though the paintings (thing) of Claude Monet are just as famous as Pablo Picasso (person), Monet's techniques remain distinct.
(The comparison incorrectly equates "paintings" to "Pablo Picasso.")
Correct: Though the paintings (thing) of Claude Monet are just as famous as the paintings of (thing) Pablo Picasso, Monet's techniques remain distinct.
Shortcut: Use "that of" (singular) to replace a repeated noun.
Correct: Though the painting style of Claude Monet is just as famous as that of Pablo Picasso, Monet's techniques remain distinct.
Shortcut: Use apostrophes for possessive comparisons.
Correct: Though the painting style of Claude Monet is just as famous as Pablo Picasso’s (= Pablo Picasso’s painting style), Monet's techniques remain distinct.

B. Plural Comparisons
Incorrect: The hummingbird’s wings beat faster than other birds.
(This sentence suggests that the wings are compared to entire birds, rather than their wings.)
Correct: The hummingbird’s wings beat faster than the wings of other birds.
Shortcut: Use "those of" (plural) to replace a repeated noun.
Correct: The hummingbird’s wings beat faster than those of other birds.
Shortcut: Use apostrophes for possessive comparisons.
Correct: The hummingbird’s wings beat faster than other birds’ (= other birds’ wings).

C. Then vs. Than (ACT-Specific Rule)
Use "than" for comparisons, not "then" (which refers to time).
Incorrect: The giraffe’s neck is much longer then that of a zebra.
Correct: The giraffe’s neck is much longer than that of a zebra.

D. Quantity Words
Use the correct word based on singular vs. plural nouns:
• Number, Many, Fewer → modify plural nouns.
Correct: Fewer people attended the event.
Incorrect: Less people attended the event.
• Amount, Much, Less → modify singular nouns.
Correct: She drank less water than before.
Incorrect: She drank fewer water than before.
To avoid faulty comparisons, always check that the items being compared are logically equivalent and use proper replacements (that of/those of) where needed.

16. Question Marks

Question marks are rarely tested on standardized exams, but they may appear occasionally.

Direct vs. Indirect Questions
Use a question mark only for direct questions—those that stand alone as complete questions.
Incorrect: Most of the research conducted by linguist Noam Chomsky focuses on one central question: how do children acquire language.
Correct: Most of the research conducted by linguist Noam Chomsky focuses on one central question: how do children acquire language?
However, when a question is indirect—embedded within a sentence—a period is used instead.
Incorrect: Researchers continue to study how early infants can recognize speech patterns?
Correct: Researchers continue to study how early infants can recognize speech patterns.

17. Shorter is Better

Avoid wordiness and redundancy (unnecessary repetition).
When multiple answer choices are grammatically correct and convey the same meaning, the shortest one is almost always correct.

Eliminating Redundancy
Consider the following sentence:
The expansion of the railway system was a major project that took place on a massive scale and required thousands of workers.
Which revision is the most concise?
A. NO CHANGE
B. a massively huge project on a large scale
C. a major project, which took place on a massive scale
D. a major project
The correct answer is D.
Why?
A project that takes place on a massive scale is already considered major, so the extra words are unnecessary. The shortest answer that retains the essential meaning is almost always the best choice.

18. Adjectives vs. Adverbs (ACT Only)

A. Adjectives vs. Adverbs

• Adjectives describe nouns:
  Examples: the colorful painting, the difficult test, the graceful dancer

• Adverbs describe verbs and usually end in -ly:
  Examples: The student wrote carefully. The wind blew fiercely.

Common Error: Using an Adjective Instead of an Adverb
Incorrect: The scientist explained the theory clear during the lecture.
Correct: The scientist explained the theory clearly during the lecture.

B. Comparatives and Superlatives

• Comparative: adjective + -er OR more + adjective
  Examples: stronger, faster, more exciting

• Superlative: adjective + -est OR most + adjective
  Examples: strongest, fastest, most exciting

  
  

Common Error: Using "more" or "most" with -er or -est
Incorrect: The latest study provided a more clearer explanation of the phenomenon.
Correct: The latest study provided a clearer explanation of the phenomenon.
Incorrect: The Pacific Ocean is the most deepest ocean in the world.
Correct: The Pacific Ocean is the deepest ocean in the world.

19. Pronoun Case (ACT Only)

When pronoun case is tested, it usually involves plural pronouns combined with proper names (e.g., "Sarah and me") or two pronouns (e.g., "him and me").

A. Proper Name + Pronoun
To determine the correct pronoun, remove the proper name and check what sounds correct.
Incorrect: Last summer, my sister and me traveled across Europe.
(Cross out "my sister": Last summer, me traveled across Europe.)
Since you would say "I traveled," the correct sentence is:
Correct: Last summer, my sister and I traveled across Europe.

B. Two Pronouns
Cross out each pronoun one at a time to see what sounds correct.
Incorrect: The teacher gave he and I extra assignments.
(Cross out "he": The teacher gave I extra assignments. → Incorrect.)
(Cross out "I": The teacher gave he extra assignments. → Incorrect.)
Correct: The teacher gave him and me extra assignments.

C. "Between" Always Takes an Object Pronoun
Use me, him, her, us, them after between.
Incorrect: The argument was between she and I.
Correct: The argument was between her and me.

20. Diction & Idioms

A. Could, Should, Would, Might HAVE (Not OF)
Always use have after these verbs, never of.
Incorrect: She could of won the race if she had trained harder.
Correct: She could have won the race if she had trained harder.

B. Prepositions and Verbs
There is no strict rule for these; they must be answered based on common usage.
Incorrect: The scientist was interested for learning about space exploration.
Correct: The scientist was interested in learning about space exploration.
Incorrect: The company was accused for unethical business practices.
Correct: The company was accused of unethical business practices.

C. Register: Formal vs. Informal
Correct answers should be neutral—neither too formal nor too informal.
Too Informal: The museum has a bunch of cool artifacts from ancient civilizations.
Too Formal: The museum possesses an exquisite assemblage of historical relics.
Just Right: The museum has a remarkable collection of historical artifacts.

Mastering these grammar rules is key to achieving a high score on the SAT and ACT, but knowing the rules is just the first step. At North American Tutors, our expert instructors provide personalized coaching to help students apply these concepts effectively and gain confidence in their test-taking skills. Sign up today and take the next step toward your dream score!