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TOEFL Grammar: Sentence foundations

10 easy-level rules, each shown with a correct sentence, the mistake learners most often make instead, and the TOEFL tasks where it counts.

Test Ninjas Research · Updated October 1, 2026

Every sentence needs a few things in place: a subject, a finite verb, and words in an order English readers expect. These rules sound basic, but missing subjects, fragments and comma-joined sentences are exactly the errors that make a Build a Sentence arrangement wrong or an email sentence read as broken.

Part of the TOEFL grammar guide: 120 rules in 12 topics. The cards are original teaching material checked against the linked references; they are not an ETS syllabus.

The rules

1. Complete statements

In ordinary written English, a statement normally needs an expressed subject and a finite verb.

Correct
The seminar begins at nine.
Common trap · incorrect
The seminar at nine.

What goes wrong: the trap leaves out “begins”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Clauses

2. Statement order

In a neutral statement with a direct object, the usual order is subject, verb, then object.

Correct
Nina submitted the form.
Common trap · incorrect
Nina the form submitted.

What goes wrong: the trap uses the same words in a different order, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Word order and focus

3. Imperative verbs

Begin a direct instruction with a base-form verb; the listener is the understood subject.

Correct
Please attach the file.
Common trap · incorrect
Please attaching the file.

What goes wrong: the trap uses “attaching” where the correct sentence has “attach”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Imperative clauses

4. Linking be

Use a form of be to connect a subject with a description or identity.

Correct
The study room is quiet.
Common trap · incorrect
The study room quiet.

What goes wrong: the trap leaves out “is”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Be

6. Weather subject it

Standard English uses it as a subject for weather expressions.

Correct
It is raining near campus.
Common trap · incorrect
Is raining near campus.

What goes wrong: the trap leaves out “It”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: It

7. Subject pronouns

Use I, he, she, we, or they in subject position.

Correct
She sent the reminder.
Common trap · incorrect
Her sent the reminder.

What goes wrong: the trap uses “Her” where the correct sentence has “She”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Pronouns: personal

8. Object pronouns

Use me, him, her, us, or them after a verb or preposition.

Correct
The tutor called me yesterday.
Common trap · incorrect
The tutor called I yesterday.

What goes wrong: the trap uses “I” where the correct sentence has “me”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Pronouns: personal

9. Dependent-clause fragments

A clause introduced by because cannot stand alone as a complete statement.

Correct
Because the lab was closed, we met online.
Common trap · incorrect
Because the lab was closed.

What goes wrong: the trap uses “closed” where the correct sentence has “closed, we met online”, so it no longer follows the rule.

Matters for: Build a Sentence · Write an Email · Take an Interview

Source: Clauses

Other grammar topics

Frequently Asked Questions

No task names grammar topics, but these rules matter most in Build a Sentence, Write an Email, Take an Interview. Build a Sentence rewards correct word order and forms directly; in emails, discussion posts and spoken answers, errors here make your meaning harder to follow.

No. ETS does not publish a grammar syllabus. These are original Test Ninjas teaching cards based on standard English usage, with links to the reference pages each rule was checked against.

Read the rule, then cover the correct sentence and try to fix the trap yourself. Next, write one new sentence of your own that follows the rule, ideally about a campus or class situation.

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