Complete TOEFL Grammar Guide: 114 Core Topics and Sentence Analysis

TOEFL grammar is less about memorizing terminology than recognizing a sentence’s core structure, verb forms, modifier relationships, and clause connections. This guide moves from basic sentence patterns to complex structures and uses typical examples to show how each construction works.

1. What Does TOEFL Grammar Actually Test?

At its core, TOEFL grammar asks one question:

Determine why an English sentence is true.

Almost all grammar questions can ultimately be traced back to several questions:

Does the sentence have a subject?

Does it contain a finite verb?

Do the subject and the predicate go together?

Why are there two verbs in one sentence?

What connection is used between the two sentences?

What should be put before the noun?

Who does the modifier modify?

Is the clause structure complete?

If you master all these questions, most of the TOEFL grammar will have been solved.

2. Core Principle 1: Basic English Sentence Structure

This is the most important chapter in the entire TOEFL grammar.

1. The minimum structure of a complete sentence

The most basic:

Subject + Verb

For example:

Birds fly.

Birds = subject

fly = predicate

No matter how complicated it is:

The students study English.

S + V + O

No matter how complicated it is:

The professor gave the students an assignment.

S + V + indirect object + direct object

3. Five basic sentence patterns in English

Almost all complex sentences are expanded from these basic structures.

TOEFL questions often use long subjects and multi-layered modifiers to lengthen sentences, and the real S and V can easily be obscured.

For example:

The rapid development of communication technologies in many developing countries has changed the way people work.

Real structure:

development has changed the way

instead of:

technologies have changed

That is because the head of the subject is:

development

4. The first major TOEFL test point: subject and predicate

This importance ranks first in the entire grammar.

1. Every independent clause needs a finite verb

Correct:

The scientist discovered a new species.

Error:

The scientist discovering a new species.

Why?

Because:

discovering ≠ predicate

It's just a present participle.

Requires:

The scientist discovered a new species.

Or:

The scientist is discovering a new species.

5. How to Identify the Main Verb

The most confusing things:

For example:

The researchers working in the laboratory discovered the problem.

Here are:

working

discovered

But only:

discovered

is the main verb.

working in the laboratory modification researchers.

6. Why can there be two verbs in one sentence?

This is an extremely important logic in TOEFL grammar.

For example:

The scientist discovered that the theory was incorrect.

Common forms include:

discovered

was

Why?

Because there are:

that

Two structures are formed:

The scientist discovered ...

and

the theory was incorrect

The second is the noun clause introduced by that.

Therefore, you can remember a very important TOEFL formula:

There must usually be a connecting structure between two complete S + V structures.

For example:

and

but

because

although

if

when

while

that

which

who

because of ❌

7. Run-on Sentences: Two Independent Clauses Cannot Be Joined Without Proper Punctuation or a Connector

Error:

The experiment failed the researchers repeated it.

There are actually two sentences here:

The experiment failed.

The researchers repeated it.

Can't fight directly.

Correct:

The experiment failed, so the researchers repeated it.

Or:

Because the experiment failed, the researchers repeated it.

8. Subject–Verb Agreement Subject–Verb Agreement

TOEFL super high frequency.

Basic principles:

singular subject → singular predicate

plural subject → plural predicate

For example:

The student works hard.

The students work hard.

The real difficulty is not the rules, but:

Find the real subject.

For example:

The effects of climate change are becoming increasingly apparent.

Not:

climate change is

real subject:

effects

So:

are

9. Prepositional phrases do not change the subject

Very important.

The number of students is increasing.

Subject:

The number

Not students.

Therefore:

The number of students is increasing.

However:

A number of students are absent.

This is the fixed difference:

the number of + plural noun + singular verb

Indicates "the quantity of...".

a number of + plural noun + plural verb

It means "many...".

10. Structures that easily lead to subject-verb agreement traps

together with

The professor, together with his students, is attending the conference.

The subject is still:

professor

as well as

The teacher, as well as the students, was invited.

along with

The president, along with several advisers, has arrived.

None of these are like and.

real:

The professor and his students are attending.

11. each / every / either / neither

Generally treated in odd numbers.

Every student is required to attend.

Each book has a different title.

Neither answer is correct.

Either option is acceptable.

12. Indefinite pronouns

Usually singular:

someone

somebody

something

anyone

anybody

anything

everyone

everybody

everything

no one

nobody

nothing

each

either

neither

For example:

Everyone has a different opinion.

13. There be structure

What really determines the verb is the noun that follows it.

There is a problem.

There are several problems.

TOEFL can be very long:

There are several important factors that influence language development.

14. Verb tenses

TOEFL is not as crazy about "tense names" as the middle school exam, but tense logic is very important.

There are four main types of time that need to be mastered in English:

past

present

future

past viewpoint

And four bodies:

simple

continuous

perfect

perfect continuous

Combined to produce various tenses.

15. Present tense

Structure:

do / does

Purpose:

Facts, patterns, habits, long-term conditions.

Water boils at 100°C.

Many animals migrate seasonally.

Very common in academic English.

Describe the general conclusions of the study:

Research shows that exercise improves cognitive performance.

16. Simple past tense

Structure:

did

Events that have ended in the past.

The researchers conducted the experiment in 2019.

Typical time:

yesterday

last year

in 1990

two years ago

17. Present perfect tense

Structure:

have/has + past participle

Core:

Happened in the past but is relevant to the present.

For example:

Scientists have discovered several new species.

Compare with the past:

Scientists discovered the species in 1998.

Past time with a definite end → simple past tense.

18. Past perfect tense

had + PP

means:

past past

For example:

By the time the researchers arrived, the animals had disappeared.

Time relationship:

animals disappeared

↓

researchers arrived

↓

Now

19. In Progress

be + V-ing

Indicates ongoing and temporary status.

The climate is changing rapidly.

Scientists are studying the phenomenon.

20. Consistent tenses

If the article talks about research that happened in the past:

The researchers collected the samples and analyzed them.

Don’t be confused:

collected ... analyze

Unless the meaning of time really changes.

21. Passive Voice Passive Voice

Very common in TOEFL Academic English.

Structure:

be + past participle

Active:

Scientists discovered the fossil.

Passive:

The fossil was discovered by scientists.

Common:

is used

was discovered

has been found

can be observed

were produced

22. The most common mistakes in passive voice

Error:

The fossil discovered in 1990.

If this were a complete sentence, it would be missing a predicate.

Should:

The fossil was discovered in 1990.

However:

The fossil discovered in 1990 is extremely rare.

Here:

discovered in 1990

It is a past participle phrase modifying fossil.

True predicate:

is

This difference is a classic TOEFL test point.

23. Modal Verbs

Important:

can

could

may

might

must

should

will

would

Structure:

modal + verb base form

Correct:

can produce

Error:

can produces

can produced

can producing

can to produce

Past speculation:

may have caused

Structure:

modal + have + PP

For example:

Climate change may have contributed to the extinction.

24. Subjunctive

TOEFL likes one in particular:

suggest / recommend / demand / insist + that + S + verb base form

For example:

The professor suggested that the student revise the paper.

Not:

revises

This form is sometimes written:

should revise

But American English often uses the original form directly.

Similar words:

recommend

suggest

propose

request

require

demand

insist

urge

25. Nonfinite Verbs: A Second Core Area of TOEFL Grammar

Three main types:

to do

doing

done

That is:

infinitive

gerund/present participle

past participle

26. To-infinitive

Structure:

to + verb

For example:

Students need to study.

Scientists attempted to explain the phenomenon.

Commonly used to do:

want

hope

plan

decide

expect

attempt

learn

need

agree

refuse

promise

27. Gerund: V-ing as a noun

For example:

Reading improves vocabulary.

Reading = subject.

Students enjoy reading.

reading = object.

Common must-dos:

enjoy

avoid

consider

finish

suggest

mind

practice

admit

For example:

The researchers considered changing the methodology.

28. V-ing is usually used after a preposition

This is a very important exam rule.

For example:

by using

without considering

before conducting

after completing

instead of doing

Error:

by use

If it is a verb meaning usually:

by using

29. to is not necessarily an infinitive

Super important.

Some to are prepositions.

For example:

look forward to seeing you.

Not:

look forward to see

Because here:

to = preposition

Similar to:

be accustomed to doing

be used to doing

object to doing

contribute to doing

lead to doing

30. Present participle V-ing

Usually expressed:

take the initiative / carry out

For example:

Students studying abroad often experience cultural differences.

Complete:

Students who study abroad...

Reduction:

Students studying abroad...

31. Past participle PP

Usually expressed:

Passive/Complete

For example:

The book written by Darwin became famous.

Complete:

The book that was written by Darwin...

Reduction:

The book written by Darwin...

So it's very important:

doing → take the initiative

done → passive

Compare:

animals living in forests

The animals themselves live.

animals affected by pollution

Animals are affected.

32. Participle structure

For example:

Using advanced technology, scientists identified the species.

The logical subjects must be consistent.

Here:

Who uses technology?

scientists。

So correct.

Error:

Using advanced technology, the species was identified by scientists.

Syntactically, a dangling modifier is produced:

It seems species is using technology.

33. Causative verbs

make

make + O + verb base form

The discovery made scientists reconsider the theory.

let

let + O + verb base form

The teacher let students leave early.

have

have + O + verb base form

The professor had the students rewrite the paper.

get

Usually:

get + O + to do

She got him to help.

34. Sensory verbs

see

hear

watch

feel

notice

Can:

I saw him leave.

Emphasis on complete movement.

Or:

I saw him leaving.

Emphasis is ongoing.

35. Nouns: countable and uncountable

TOEFL likes it very much.

Countable:

student

book

idea

theory

animal

Uncountable:

information

research

evidence

knowledge

equipment

furniture

advice

So:

Error:

an information

Correct:

information

Error:

many research

Usually:

much research

Or:

many studies

Thirty-six. Countable odd numbers cannot be streaked

This is a very important rule in English.

Cannot:

Student entered classroom.

Usually it is necessary to:

A student entered the classroom.

Or:

The student...

Or:

My student...

So:

Singular countable nouns usually must be preceded by determiner.

37. Article a / an

means:

one, some, unspecified object

For example:

Scientists conducted an experiment.

appears for the first time.

Thirty-eight, the

Indicates a specific object that both parties can identify.

Scientists conducted an experiment.

First time:

an experiment

Then:

The experiment lasted three months.

Everyone knows which one to refer to the second time, so the.

Thirty-nine, zero article

Refers to the plural:

Dogs are social animals.

Not:

The dogs are social animals.

If referring to all dogs:

Uncountable refers to:

Water is essential for life.

Forty, pronoun

Need to master:

subject：

I / he / she / we / they

object：

me / him / her / us / them

possessive adjective：

my / his / her / our / their

possessive pronoun：

mine / his / hers / ours / theirs

For example:

Scientists examined their results.

instead of:

them results

41. it / its / it's

High frequency basic errors:

its = its

The animal changes its behavior.

it's = it is / it has

It's difficult.

42. Adjectives and adverbs

Adjective modification:

noun

For example:

a significant difference

Adverb modification:

verb

adjective

adverb

whole sentence

For example:

change significantly

highly significant

Classic TOEFL questions:

The results were ______ different.

Answer:

significantly

Because different is an adjective, it needs to be modified by an adverb.

Forty-three, -ed / -ing adjective

Difference:

interesting = interesting

interested = feel interested

For example:

The lecture was interesting.

The students were interested.

Similar to:

boring / bored

exciting / excited

surprising / surprised

confusing / confused

Forty-four, comparative degree

General:

A is taller than B.

Long words:

more important than

For example:

Solar energy is more environmentally friendly than coal.

Forty-five, the most advanced

the + superlative

For example:

the largest

the most important

Forty-six, as...as

as + adjective/adverb + as

For example:

This method is as effective as the traditional method.

Error:

as effective than

47. Comparisons must be logically corresponding

I really like taking the TOEFL test.

Error:

The climate of Canada is colder than Mexico.

The actual comparison is:

Canada's climate

and

Mexico the country

The logic is not parallel.

Should:

The climate of Canada is colder than that of Mexico.

that = climate

Plural:

those of

For example:

The temperatures in Canada are lower than those in Mexico.

48. Parallelism

This is extremely important advanced grammar for TOEFL.

Error:

The course teaches students to read, writing, and speak.

Should:

to read, write, and speak

Keep the structure consistent.

Or:

reading, writing, and speaking

Forty-nine, both...and

Must be parallel:

She is both intelligent and hardworking.

fifty, either...or

Students can either study abroad or remain at home.

Fifty-one, neither...nor

The theory is neither accurate nor useful.

Fifty-two, not only...but also

The technology not only reduces costs but also improves efficiency.

Be sure to note that the structure on both sides is consistent.

Error:

not only reducing costs but also improves efficiency

Fifty-three, prepositions

TOEFL is not mainly about memorizing prepositions, but there are many fixed collocations.

Common:

depend on

result in

result from

contribute to

lead to

consist of

belong to

participate in

focus on

be responsible for

be associated with

be interested in

be capable of

Fifty-four, because and because of

This is a classic structural question.

because + S + V

The game was canceled because it was raining.

because of + noun

The game was canceled because of the rain.

Cannot:

because of it was raining

Fifty-five, although and despite

Likewise:

although + S + V

Although the weather was bad, we continued.

And:

despite + noun

Despite the bad weather, we continued.

Also possible:

despite the fact that + S + V

56. Connectives are one of the cores of TOEFL grammar

Connect two complete sentences:

and

but

or

so

yet

For example:

The experiment failed, so the researchers tried again.

Fifty-seven, subordinating conjunctions

because

although

though

even though

while

whereas

if

unless

when

before

after

since

as

They can create a clause.

For example:

Although the experiment failed, researchers obtained useful data.

Fifty-eight, noun clauses

This is the core of TOEFL long and difficult sentences.

Main guiding words:

that

whether

if

what

who

why

how

where

when

For example:

Scientists believe that climate change affects migration.

Whole:

that climate change affects migration

It is equivalent to a noun and is the object of believe.

Fifty-nine, that clause

Researchers discovered that the species was endangered.

Structure:

Researchers = subject

discovered = predicate

that...

Inside:

species = subject

was = predicate

Sixty, what clause

Very important:

Scientists do not know what caused the extinction.

what itself acts as an element in the clause.

Compare:

Scientists know that climate change caused the extinction.

that does not itself serve as the subject or object of caused.

Sixty-one, whether

means "whether".

Researchers are uncertain whether the treatment is effective.

62. Noun clauses use declarative word order

This is where Chinese students are particularly prone to making mistakes.

Direct questions:

Where does he live?

Clause:

I don't know where he lives.

Not:

I don't know where does he live.

Likewise:

Do you know why the experiment failed?

Not:

why did the experiment fail

63. Attributive Clause Relative Clause

TOEFL is super important.

Modify noun:

The scientist who discovered the element won a prize.

who modifies scientist.

64. Relative pronouns

who

Person:

the scientist who discovered it

whom

person, accusative case:

the scientist whom we interviewed

In modern English, it is often direct who.

which

Object:

the theory which explains the phenomenon

that

person or thing, restrictive clause:

the theory that explains the phenomenon

whose

Belongs to:

the scientist whose research changed biology

Sixty-five, relative adverbs

where

the laboratory where the experiment was conducted

when

the year when the discovery occurred

why

the reason why the experiment failed

66. How to Analyze Relative Clauses

Check whether the clause is missing something.

For example:

The book _____ changed biology was published in 1859.

Behind:

_____ changed biology

Missing subject.

So:

that / which

Additionally:

The book _____ Darwin wrote was published in 1859.

Darwin wrote _____

Missing object.

So:

that / which

However:

The year _____ Darwin published the book...

Darwin published the book _____

The structure is complete, only the time information is missing.

So:

when

67. Restrictive and non-restrictive attributive clauses

Restrictions:

Students who study regularly generally perform better.

Not all students.

Non-limiting:

Darwin, who developed the theory of evolution, was born in 1809.

Commas indicate additional information.

Usually:

You cannot use that in a non-restrictive attributive clause.

Sixty-eight, preposition + which / whom

Common Academic English:

the method by which the data were collected

the scientist with whom she worked

the conditions under which the experiment was conducted

This is especially common in TOEFL reading.

69. Reduction of attributive clauses

Complete:

Animals that live in cold climates often have thick fur.

Reduction:

Animals living in cold climates often have thick fur.

Active → V-ing.

Complete:

The samples that were collected in Africa were analyzed.

Reduction:

The samples collected in Africa were analyzed.

Passive → PP.

This is one of the most important long and difficult sentence structures in TOEFL.

70. Adverb clauses

means:

time

Reason

Conditions

give in

purpose

result

Contrast

For example:

Time:

When temperatures fall, animals migrate.

Reason:

Animals migrate because food becomes scarce.

Concession:

Although temperatures were low, the plants survived.

Conditions:

If temperatures continue to rise, ecosystems will change.

Seventy-one, conditional sentences

Basic conditional sentences:

If water reaches 100°C, it boils.

Facts.

First condition:

If temperatures rise, sea levels will increase.

Realistically possible.

Second condition:

If I had more time, I would study more.

Now suppose.

Third condition:

If scientists had discovered the problem earlier, they might have prevented the damage.

Past counterfactuals.

Seventy-two, inversion

This is TOEFL Advanced Grammar.

Normal:

The phenomenon rarely occurs.

Flip:

Rarely does the phenomenon occur.

Common trigger words:

never

rarely

seldom

hardly

scarcely

little

not only

only then

only after

under no circumstances

For example:

Never has this phenomenon been observed before.

Seventy-three, Not only Flip

If the beginning of the sentence:

Not only did the experiment fail, but it also damaged the equipment.

Note:

Use after did:

fail

Not failed.

Seventy-four, Only + adverbial at the beginning of the sentence

Only after several experiments did scientists discover the cause.

Not:

did scientists discovered

Because the word did must be followed by its original form.

Seventy-five, So/Neither inversion

John likes science, and so does Mary.

John doesn't like science, and neither does Mary.

76. Emphasis on structure It is...that...

It was Darwin who proposed the theory.

Basic sentences:

Darwin proposed the theory.

Emphasis on Darwin:

It was Darwin who proposed the theory.

77. It serves as the formal subject

It is important to understand the difference.

Real content:

to understand the difference

Also possible:

It is important that students understand the difference.

Seventy-eight, There + be

Indicates existence:

There are several explanations for the phenomenon.

Not to be confused with:

They are...

Confused.

Seventy-nine, apposition

TOEFL reading is super common:

Darwin, a British naturalist, developed the theory of evolution.

a British naturalist and Darwin are the same person.

This insertion structure often interferes with predicate recognition.

Real sentence:

Darwin developed the theory.

80. Appositive clauses

The theory that climate change caused the extinction remains controversial.

Here the that clause is explained:

the content of the theory.

Note that it is different from the attributive clause.

Attributive clause:

The theory that explains the extinction...

that serves as the subject in the clause.

Appositive:

The theory that climate change caused the extinction...

Clause:

climate change caused the extinction

The structure itself is complete.

81. Comparative Structure

Except:

more...than

Also need to master:

the more..., the more...

For example:

The more students practice, the better they perform.

Eighty-two, multiple structure

twice as large as

three times as much as

four times the size of

For example:

Jupiter is approximately eleven times as wide as Earth.

Eighty-three, quantifiers

Countable:

many

few

a few

fewer

number

Uncountable:

much

little

a little

less

amount

For example:

fewer students

Not:

less students

Pay special attention to the formal examination of English.

eighty-four, few and a few

The difference is huge.

few students

There are almost no students, so I tend to be negative.

a few students

A few students were more positive.

Same reason:

little evidence

There is little evidence.

a little evidence

There is some evidence.

Eighty-five, another / other / others / the other

This is classic exam grammar.

another

another + singular

another method

other

other + plural/uncountable

other methods

others

Pronoun alone:

Some students agreed; others disagreed.

the other

The other of the two:

One method is expensive; the other is inexpensive.

Eighty-six, one...another...

Multiple objects:

One theory suggests A; another suggests B.

Two objects:

One is large; the other is small.

87. Identifying Parts of Speech

TOEFL is very important.

For example:

rapid development

rapid = adjective

development = noun

develop rapidly

develop = verb

rapidly = adverb

Common suffixes:

For example:

significant

adjective.

significance

noun.

significantly

adverb.

88. Word Order

Ordinary declarative sentences:

Subject + Verb + Object

For example:

Scientists discovered the species.

English cannot be adjusted casually like Chinese.

89. Position of adjectives

Usually:

adjective + noun

an important discovery

Or after a linking verb:

The discovery was important.

Cannot:

the discovery importantly

90. Position of adverbs

Adverb of frequency:

always

usually

often

sometimes

rarely

never

General:

Before ordinary verbs:

Scientists often conduct experiments.

after be:

The results are often inaccurate.

91. Word order of interrogative sentences

General questions:

Do students need textbooks?

Special questions:

Why do students need textbooks?

be：

Why is the theory important?

But again note:

Embedded clause:

Scientists want to know why the theory is important.

Not:

why is the theory important

92. Active and Passive Choices

It depends on whether the subject performs the action or undergoes the action.

Scientists conducted the experiment.

Scientists do experiments.

The experiment was conducted by scientists.

experiment is done.

This will directly determine:

doing / done

For example:

researchers conducting the experiment

experiments conducted by researchers

Ninety-three, verb collocations

A large number of TOEFL grammatical errors actually belong to:

verb pattern

For example:

prevent A from doing B

allow A to do B

enable A to do B

require A to do B

encourage A to do B

cause A to do B

keep A from doing B

These are well worth carrying alone.

Ninety-four, Allow

Correct:

allow students to use calculators

Error:

allow students use calculators

Ninety-five, Prevent

prevent animals from entering the area

Not:

prevent animals to enter

Ninety-six, Help

Either:

help students understand

help students to understand

Ninety-seven. Used to / be used to / be used for

Very easy to mix.

used to + verb base form

In the past:

People used to believe that the Earth was flat.

be used to + noun / doing

Habits:

Students are used to studying late.

be used to do

is used for:

This instrument is used to measure temperature.

be used for doing

This instrument is used for measuring temperature.

Ninety-eight, Had better

had better + verb base form

You had better study.

Not:

had better to study

Ninety-nine, Would rather

would rather + verb base form

I would rather stay home.

One hundred, Prefer

Can:

prefer A to B

prefer doing A to doing B

prefer to do A rather than do B

Keep parallel.

101. Avoid double conjunctions

Thinking in Chinese is very easy:

Error:

Although the experiment failed, but researchers learned something.

English:

Although the experiment failed, researchers learned something.

Or:

The experiment failed, but researchers learned something.

Likewise:

Error:

Because it rained, so we stayed home.

102. Commas cannot directly connect two complete sentences.

Error:

The experiment failed, the researchers tried again.

This is:

comma splice

Should:

The experiment failed, so the researchers tried again.

Or:

The experiment failed; the researchers tried again.

Or:

Because the experiment failed, the researchers tried again.

103. The "long subject" that TOEFL particularly likes

For example:

The rapid expansion of cities in developing countries has created serious environmental problems.

Don't see:

countries

Just choose:

have

The core of the entire subject:

expansion

So:

has。

104. Insert ingredient trap

The professor, along with several graduate students, is conducting the research.

Delete insert:

The professor is conducting the research.

This method of "removing distractions" is very effective when doing grammar questions.

105. Complex noun structure

Academic English Plenty:

the development of modern transportation systems

Core words:

development

All:

of modern transportation systems

Just embellishment.

No matter how complicated it is:

the effects of increasing global temperatures on marine ecosystems

Core:

effects

So:

The effects ... are significant.

106. Classic Structure questions of TOEFL ITP

This type of question usually looks like this:

_____ one of the most important discoveries in modern medicine.

When solving a problem, don’t look at the meaning first, check the structure first.

First ask:

What is missing from this sentence?

If there is no predicate after it, the space may be needed:

The discovery was...

Or can form a complete S+V structure.

The Structure question really tests:

Which structural component is missing from the sentence?

TOEFL ITP Structure focuses on identifying correct and incorrect sentence structures in standard written English.

107. Written Expression question

Another typical question:

Mark the four parts A/B/C/D in a complete sentence.

For example:

The animals was observed in several different environments.

Need to find:

was

Because:

animals → were

Written Expression usually takes this form: Find the error in four highlighted words or phrases.

108. How to do Build a Sentence in 2026 TOEFL iBT

iBT Writing now clearly requires:

Rearrange the given words or phrases to form complete, grammatical sentences or questions.

This task mainly examines the English sentence structure understanding.

The following is a simulation:

because of / was canceled / the outdoor event / heavy rain

Find first:

Subject:

the outdoor event

Predicate:

was canceled

Reason:

because of heavy rain

Answer:

The outdoor event was canceled because of heavy rain.

There is no need to try out word by word, you should first identify the sentence skeleton.

109. The most effective method of Building a Sentence

After seeing a bunch of word chunks, the brain processes them in this order:

S → V → O/C → clause → modifier

For example:

have shown / regular exercise / several recent studies / that / improves memory

The first step is to find the subject:

several recent studies

Second step predicate:

have shown

The third step requires content after show:

that...

Fourth step clause:

regular exercise improves memory

Get:

Several recent studies have shown that regular exercise improves memory.

This is the real core competency of TOEFL grammar.

110. A particularly important "sentence analysis formula"

When you see any long TOEFL sentences in the future, you can follow:

① Circle predicate

↓

② Find the subject corresponding to each predicate

↓

③ Determine how many S+V there are

↓

④ Find connecting words

↓

⑤ Temporarily delete prepositional phrases, participles, and parentheses

↓

⑥ Distinguish between main clause and subordinate clause

For example:

Although many scientists initially rejected the theory, evidence collected during subsequent experiments gradually convinced researchers that the hypothesis was correct.

First, identify the finite verbs:

rejected

convinced

was

Three.

Then:

Although many scientists rejected the theory,

First level clause.

evidence ... convinced researchers

Main clause.

that the hypothesis was correct

Object clause.

And:

collected during subsequent experiments

Collected during subsequent experiments contains no finite verb; collected is a past participle modifying evidence.

The entire super long sentence is clear at once.

111. TOEFL Grammar Priorities

If the learning goal isImprove your TOEFL score as quickly as possible, the priority of each grammar module is not the same.

It can be divided into the following three levels:

S level: must be fully mastered

Sentence stem S + V

subject-verb agreement

Finite vs. nonfinite verbs

doing / done / to do

active/passive

clause connectives

noun clause

attributive clause

adverb clause

parallel structure

part of speech

These solve a large number of problems and directly affect reading long and difficult sentences and writing.

Level A: Very important

tense

completed

modal verb

article

Countable and uncountable

pronoun

Comparative

preposition collocation

conditional sentence

participle reduction

compare structures

Level B: Completion in stages with high scores

Flip

Subjunctive mood

Emphasis on structure

appositive clause

Complex comparison

Special fixed combination

Advanced word segmentation structure

112. The 15 Core TOEFL Grammar Modules

When learning the system, it is suitable to proceed in the following order:

113. Errors to Recognize on Sight

For example, see:

The development of new technologies have...

Be alert now.

development = singular:

has

See:

Scientists interested to study...

Be alert now.

interested in studying

See:

The animals living in the forest is...

Subject:

animals

So:

are

See:

Although X, but Y

Be alert now.

Delete but.

See:

because of the temperature increased

Be alert now.

because of + noun.

Either:

because the temperature increased

Either:

because of the increase in temperature

See:

the experiment conducting by scientists

Be alert now.

experiment is conducted:

conducted

See:

researchers don't know why did the species disappear

Be alert now.

Noun clauses use declarative word order:

why the species disappeared

See:

allow students use

Be alert now:

allow students to use

See:

by use technology

Be alert now:

by using technology

See:

more easier

Be alert now.

Cannot double compare:

easier

See:

informations / researches / equipments

Be alert now.

General:

information / research / equipment

114. The grammar level really needed for high TOEFL iBT scores

High scores do not require deliberately writing:

Had it not been for the unprecedented proliferation of technological advancements...

This intentionally complicated English.

TOEFL Writing is more importantUse grammar and vocabulary accurately and express ideas clearly and effectively. Clear, organized expression is more important than deliberately stacking complex structures.

So the real high-scoring ability is:

Make no mistakes in simple sentences + be able to control complex sentences.

For example, instead of writing a 50-word sentence with a lot of errors, it is better to master the control:

Although X, Y.

X because Y.

Studies have shown that X.

X, which Y, can Z.

If X occurs, Y may happen.

One reason is that X.

Not only X but also Y.

Write these structures asStable, accurate and natural, the value is much higher than memorizing a lot of unpopular grammar.

TOEFL Grammar Knowledge Map

The entire system can be summarized as:

English sentences

→ trunk

S / V / O / C

→ verb system

Tense / Voice / Modality / Subject-verb agreement

→ Nonfinite verbs

to do / doing / done

→ noun system

Singular and plural / countable and uncountable / article / pronoun

→ Modification system

adjective/adverb/preposition/comparison

→ Connect the system

and / but / because / although...

→ Three major clauses

Noun clause / attributive clause / adverb clause

→ complex structure

Participle reduction/parallel/comparison/condition/inversion/virtual/emphasis

As long as this system is fully mastered, the core grammar required for TOEFL is basically complete.

For the 2026 TOEFL iBT, the most useful priorities are sentence structure, Build a Sentence, complex-sentence analysis, and practical editing in writing. There is little value in giving every chapter of a traditional grammar book equal study time. Because the Writing section includes Build a Sentence and contains 12 items in about 23 minutes, grammatical decisions need to become fast and automatic.