Grammar 101: Complete TOEFL Grammar Guide with Examples

Why Grammar Matters for TOEFL

Grammar isn't just about following rules; it's about communicating clearly and effectively. Strong grammar skills will boost your scores across all four TOEFL sections:

Speaking: Demonstrate language use and grammatical range
Writing: Craft coherent, error-free essays under time pressure
Reading: Understand complex sentence structures and relationships
Listening: Parse rapid speech and follow multi-clause statements

Study Tip: Focus on understanding patterns, not just memorizing rules. Practice recognizing and using these structures in context, not in isolation.

1. Sentence Structure

Understanding sentence types is fundamental to TOEFL success. You'll encounter complex structures in reading passages and need to produce varied sentences in speaking and writing.

Simple Sentences

One independent clause with a subject and verb.

Example: "The professor lectures every Tuesday."

Compound Sentences

Two or more independent clauses joined by coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so).

Example: "She studied hard, but she still felt nervous about the exam."

Complex Sentences

One independent clause and at least one dependent clause.

Example: "Although it was raining, we continued our field research."

Compound-Complex Sentences

Multiple independent clauses and at least one dependent clause.

Example: "When the lecture ended, students asked questions, and the professor answered them thoroughly."

TOEFL Strategy: In the Writing section, use a mix of sentence types to demonstrate grammatical range. However, prioritize clarity over complexity. A clear simple sentence is better than a confusing complex one.

2. Verb Tenses

Mastering verb tenses is critical for expressing time relationships accurately. The TOEFL tests your ability to use tenses correctly in various contexts.

Present Tenses

Present Simple: Habitual actions, general truths, scheduled events

Example: "Water boils at 100 degrees Celsius." | "She studies every evening."

Present Continuous: Actions happening right now, temporary situations

Example: "I am currently researching climate change." | "They are living in Tokyo this semester."

Present Perfect: Actions with relevance to the present, experiences, duration from past to present

Example: "Scientists have discovered a new species." | "I have studied English for five years."

Past Tenses

Past Simple: Completed actions at a specific time in the past

Example: "The researcher conducted the experiment last month."

Past Continuous: Actions in progress at a specific moment in the past

Example: "While I was reading the passage, I was taking notes."

Past Perfect: Actions completed before another past action

Example: "By the time the lecture started, most students had already arrived."

Future Forms

Will: Spontaneous decisions, predictions, promises
Going to: Planned actions, predictions based on evidence
Present Continuous: Fixed arrangements in the near future

Examples: "I will help you with that." | "I'm going to take the TOEFL next month." | "We are meeting the advisor tomorrow at 2 PM."

Common Mistake: Don't use present perfect with specific past time expressions.

Incorrect: "I have studied yesterday."

Correct: "I studied yesterday." or "I have studied recently."

3. Subject-Verb Agreement

Subjects and verbs must agree in number (singular or plural). This seems simple but can be tricky in complex sentences, a common trap in TOEFL questions.

Basic Rules

Singular subjects take singular verbs
Plural subjects take plural verbs

Examples: "The student writes an essay." | "The students write essays."

Tricky Cases

Phrases between subject and verb: The verb agrees with the subject, not the nearest noun

Example: "The results of the experiment are surprising." (subject = results, plural)

Collective nouns: Usually singular in American English

Example: "The team is conducting research." | "The faculty has approved the proposal."

Indefinite pronouns: Everyone, everybody, each, either, neither are singular

Example: "Each of the students has a different perspective."

Either/neither with or/nor: The verb agrees with the nearest subject

Example: "Neither the professor nor the students were present."

Watch Out: In reading passages, pay attention to long modifying phrases that separate the subject from the verb. This is where TOEFL tries to trick test-takers.

4. Modals & Conditionals

Modal verbs express ability, possibility, permission, and obligation. Conditionals describe hypothetical situations. Both are essential for sophisticated TOEFL responses.

Modal Verbs

Can/Could: Ability, possibility, permission
May/Might: Possibility, permission (formal)
Must/Have to: Necessity, obligation
Should/Ought to: Advice, recommendation
Would: Polite requests, hypothetical situations

Examples:
"Students must submit their assignments by Friday."
"The results might indicate a correlation."
"You should review your notes before the exam."

Conditional Sentences

Zero Conditional: General truths (If + present, present)

Example: "If you heat water to 100°C, it boils."

First Conditional: Real future possibility (If + present, will + base verb)

Example: "If I study hard, I will pass the TOEFL."

Second Conditional: Hypothetical present/future (If + past simple, would + base verb)

Example: "If I had more time, I would read all the supplementary materials."

Third Conditional: Hypothetical past (If + past perfect, would have + past participle)

Example: "If I had studied more, I would have scored higher."

TOEFL Strategy: Use conditionals in Speaking Task 1 (opinion questions) and Writing Task 2 (discussion) to express nuanced arguments: "If universities invested more in research, students would benefit from..."

5. Articles & Determiners

Articles (a, an, the) and determiners specify whether you're talking about something specific or general. This can be challenging for non-native speakers but is crucial for natural-sounding English.

Indefinite Articles (A/An)

Use with singular countable nouns when being non-specific.

A: Before consonant sounds
An: Before vowel sounds

Examples: "I need a book." | "She gave an excellent presentation." | "A university (sounds like 'yoo')" | "An hour (silent 'h')"

Definite Article (The)

Use when referring to something specific or previously mentioned.

Examples:
"I bought a book. The book is about biology." (specific book)
"The sun rises in the east." (unique thing)
"The students in this class are hardworking." (specific group)

No Article (Zero Article)

Don't use articles with:

Plural nouns in general statements
Uncountable nouns in general statements
Most countries, languages, academic subjects

Examples: "Students need to study regularly." | "Water is essential for life." | "I study biology."

Other Determiners

This, that, these, those, some, any, many, much, few, little, each, every

Examples: "These results are significant." | "Some students prefer online learning." | "Many researchers support this theory."

Common Mistake: Don't use "the" with general plural or uncountable nouns.

Incorrect: "The water is important." (general statement)

Correct: "Water is important." or "The water in this lake is polluted." (specific)

6. Prepositions

Prepositions show relationships between words, particularly relationships of time, place, and direction. They're often idiomatic and require practice to master.

Prepositions of Time

At: Specific times ("at 3 PM", "at noon", "at night")
On: Days and dates ("on Monday", "on July 4th", "on my birthday")
In: Longer periods ("in 2024", "in summer", "in the morning")

Example: "The exam is at 9 AM on Friday in December."

Prepositions of Place

At: Specific points ("at the entrance", "at home", "at the university")
On: Surfaces ("on the table", "on the wall", "on page 5")
In: Enclosed spaces ("in the room", "in the book", "in New York")

Common Prepositional Phrases (Fixed Expressions)

Many prepositions form fixed phrases with verbs, adjectives, and nouns:

Depend on, focus on, concentrate on, rely on
Interested in, participate in, succeed in, believe in
Responsible for, famous for, apologize for, search for
Agree with, cope with, deal with, provide someone with

Examples:
"The study focuses on climate patterns."
"Students should participate in class discussions."
"The professor is responsible for grading exams."

Study Tip: Learn prepositions in context, not in isolation. Keep a notebook of common prepositional phrases you encounter in reading passages and listening lectures.

7. Pronouns & Reference

Pronouns replace nouns to avoid repetition. Understanding pronoun reference is crucial for reading comprehension and producing cohesive writing.

Types of Pronouns

Subject pronouns: I, you, he, she, it, we, they
Object pronouns: me, you, him, her, it, us, them
Possessive pronouns: mine, yours, his, hers, its, ours, theirs
Possessive adjectives: my, your, his, her, its, our, their
Reflexive pronouns: myself, yourself, himself, herself, itself, ourselves, themselves

Examples:
"She completed her research by herself."
"The students submitted their essays. The professor graded them quickly."

Pronoun-Antecedent Agreement

Pronouns must agree with their antecedents (the nouns they replace) in number and gender.

Incorrect: "Each student must submit their essay." (each = singular, their = plural)

Correct: "Each student must submit his or her essay." or "Students must submit their essays."

Clear Reference

Make sure it's clear what each pronoun refers to. Ambiguous references confuse readers.

Ambiguous: "The professor talked to the student about his research." (Whose research?)

Clear: "The professor talked to the student about the student's research."

Reading Strategy: Many TOEFL reading questions ask "what does 'it' refer to in line X?" Practice identifying antecedents by working backward from pronouns to the nouns they replace.

8. Adjectives & Adverbs

Adjectives describe nouns; adverbs modify verbs, adjectives, or other adverbs. Using them correctly adds precision and sophistication to your language.

Adjectives

Adjectives come before nouns or after linking verbs (be, seem, appear, become).

Examples: "The challenging assignment took hours." | "The assignment was challenging."

Adverbs

Adverbs often end in -ly and answer questions like how, when, where, or to what extent.

Examples:
"She spoke clearly." (how?)
"The experiment was carefully designed." (how?)
"The results are extremely significant." (to what extent?)

Adjective vs. Adverb

Don't confuse adjectives with adverbs:

Incorrect: "She performed good on the test."

Correct: "She performed well on the test." (well = adverb modifying performed)

Comparative and Superlative Forms

Short adjectives: -er/-est (tall → taller → tallest)
Long adjectives: more/most (important → more important → most important)
Irregular: good → better → best; bad → worse → worst

Examples:
"This method is more effective than the previous one."
"This is the most comprehensive study on the topic."
"Her score was better than mine."

Common Mistake: Don't use double comparatives or superlatives.

Incorrect: "more easier", "most fastest"

Correct: "easier", "fastest"

9. Conjunctions & Clauses

Conjunctions connect words, phrases, and clauses. Mastering them allows you to express complex relationships between ideas. These skills are essential for high TOEFL scores.

Coordinating Conjunctions (FANBOYS)

Connect equal grammatical elements: For, And, Nor, But, Or, Yet, So

Examples:
"She studied hard, but she was still nervous."
"The lecture was long, yet it was informative."
"He didn't study, so he failed the exam."

Subordinating Conjunctions

Introduce dependent clauses that cannot stand alone:

Time: when, while, before, after, until, since, as soon as
Cause: because, since, as
Condition: if, unless, provided that
Contrast: although, though, even though, whereas, while
Purpose: so that, in order that

Examples:
"Although the topic was difficult, students understood it."
"Because she practiced daily, her pronunciation improved."
"I studied hard so that I would pass the exam."

Correlative Conjunctions

Work in pairs: both...and, either...or, neither...nor, not only...but also

Examples:
"The course covers both theory and practice."
"Not only did she pass but also she got the highest score."

Relative Clauses

Introduced by relative pronouns: who, whom, whose, which, that, where, when

Defining (essential): No commas, necessary for meaning
Non-defining (extra info): Commas required, adds information

Examples:
"The student who studied hard passed." (defining - which student?)
"Dr. Smith, who has taught for 20 years, is retiring." (non-defining - extra info)

Writing Strategy: Use a variety of conjunctions to show different relationships: contrast (although, whereas), cause-effect (because, therefore), addition (furthermore, moreover). This demonstrates sophisticated language use.

10. Common Grammar Errors

Being aware of these frequent mistakes will help you avoid them under test pressure. Review these carefully. They appear often in TOEFL contexts.

1. Run-on Sentences

Two independent clauses incorrectly joined without proper punctuation.

Incorrect: "I love studying I study every day."

Correct: "I love studying. I study every day." or "I love studying, and I study every day."

2. Sentence Fragments

Incomplete sentences missing a subject or verb.

Incorrect: "Because I was tired."

Correct: "I went to bed early because I was tired."

3. Misplaced Modifiers

Descriptive phrases placed far from what they describe, causing confusion.

Incorrect: "She served sandwiches to the guests on paper plates." (Were guests on plates?)

Correct: "She served sandwiches on paper plates to the guests."

4. Comma Splices

Two independent clauses joined with only a comma.

Incorrect: "The lecture was interesting, I took detailed notes."

Correct: "The lecture was interesting, so I took detailed notes." or "The lecture was interesting; I took detailed notes."

5. Double Negatives

Using two negative words in the same clause (creates a positive meaning or is grammatically incorrect).

Incorrect: "I don't know nothing about it."

Correct: "I don't know anything about it." or "I know nothing about it."

6. Confusing Similar Words

Its vs. It's: Its = possessive; It's = it is
Their, There, They're: Their = possessive; There = place; They're = they are
Affect vs. Effect: Affect = verb (to influence); Effect = noun (result)
Then vs. Than: Then = time; Than = comparison

Examples:
"The study had its limitations. It's important to note them."
"Their research is over there. They're presenting it tomorrow."
"This will affect the results. The effect is significant."

Under Time Pressure: These errors slip in when you're rushing. In the Writing section, save 2-3 minutes at the end to proofread specifically for these common mistakes.

What's Next?

This guide provides the foundation, but grammar mastery comes from practice and application. Here's how to take your grammar skills to the next level:

Immediate Action Steps

Practice in Context: Use these grammar structures in all four TOEFL sections
Read Actively: Analyze sentence structures in reading passages
Record Yourself: Listen for grammatical errors in your speaking
Get Feedback: Use PrepEx's AI grading to identify your weak areas
Build Habits: Focus on one grammar point per week until it becomes automatic

Pro Tip: Don't try to master everything at once. Identify your 2-3 weakest areas from this guide and focus on those first. Quality over quantity.

Advanced Resources

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Practice What You've Learned

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Grammar Practice Exercises

Grammar 101

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