Subject and verb: what every sentence needs

Short answer: Every English sentence needs a subject and a verb. The subject tells who or what the sentence is about. The verb tells what the subject does or is. Birds fly: Birds is the subject and fly is the verb. Without both, the sentence is not complete.

▶ Open the rule card · ✏️ Practice this rule

At a glance

Part	Job	Example
subject	who or what	Birds, The baby, We
verb	what they do or are	fly, cries, run, is
subject + verb	a complete sentence	Birds fly.

In short

Every sentence: subject + verb.
Subject = who or what.
Verb = what they do or are.

What is the rule for “Subject + Verb”?

The rule

Every sentence needs a subject and a verb.

How it looks

Subject + Verb: Birds fly. The baby sleeps.

What it means

The subject tells who or what. The verb tells what they do or are.

When to use it

In every sentence.

How it works

Ask: who or what is the sentence about? That is the subject.
Ask: what do they do, or what are they? That is the verb.
Check that the sentence has both. Is happy is missing a subject. My brother tall is missing a verb.
Put the subject first and the verb next: Subject + Verb.

Examples of “Subject + Verb”

Birds/n fly/v.
Who? Birds. Verb: fly.
The/art baby/n cries/v.
Who? The baby. Verb: cries.
We/pr run/v.
Who? We. Verb: run.
The/art sun/n shines/v.
What? The sun. Verb: shines.
The dog barks.
Who? The dog. Verb: barks.
My friends laugh.
Who? My friends. Verb: laugh.
Rain falls.
What? Rain. Verb: falls.
She is a teacher.
Who? She. Verb: is.

Common mistakes with “Subject + Verb”

~~Is happy.~~ → She is happy.
Who is happy? Add the subject.
~~My brother tall.~~ → My brother is tall.
Every sentence needs a verb: is.
~~Runs fast.~~ → The boy runs fast.
A sentence needs a subject. Who runs? Add The boy.
~~The sky blue.~~ → The sky is blue.
A sentence needs a verb. Add is.

Exceptions: watch out

Sit down! Look!
In instructions we do not say the subject. It is you.

Subject, verb or object?

The subject does the action. The object receives it. Some sentences have only a subject and a verb. Others add an object.

Sentence	Subject	Verb	Object
Birds fly.	Birds	fly	none
The boy kicks a ball.	The boy	kicks	a ball
I eat an apple.	I	eat	an apple

Check yourself

What is the subject? “The baby cries.”
Show the answer
The baby The subject tells who the sentence is about.
What is the verb? “We run.”
Show the answer
run The verb tells what we do.
Fix this: “Is tall.”
Show the answer
She is tall. The sentence has a verb but no subject.

How to practice “Subject + Verb”

The interactive version adds step-by-step help, spoken instructions and a quick check. One rule card, one sound lesson and the first lesson of every stone are free to try; the rest is part of Full Access. See Full Access.

Practice lesson: Sentence basics: who + does + what

Questions

Can a sentence have only a verb?

Yes, in instructions. Sit down! has no spoken subject, because the subject is you. In ordinary statements, always say the subject.

Is “is” a verb?

Yes. Is, am and are are forms of the verb be. They are needed even with no action: She is happy.

How long can a subject be?

It can be one word (Birds) or a group of words (The little baby next door). Find the verb first, then ask who or what does it.

More Sentence Building rules

Verbs can have an object: Some verbs can have an object: the person or thing that gets the action.
Present simple: I, you, we, they: For things we do again and again, and for likes, use the plain action word with I, you, we and they.
Present simple: he, she, it + -s: With he, she, it or one name, the action word usually adds -s.
Negatives: not with be and can: To say no with am, is, are or can, add not: I am not, she isn't, they aren't, it can't.
Negatives: don't and doesn't: To say no with an action word, use don't or doesn't and then the plain action word.
Yes/No questions and short answers: A yes/no question starts with the helper: am, is, are, do, does or can.

Used in these writing topics

Part of the 📘 Grammar tool. Level G2: Sentence Building. Đọc bằng tiếng Việt.

Written for English learners by the English for Fun team. How we write our lessons · Last updated 2026-11-05.

Reviewed by Chinh Q. Hoang, PhD, founder, English for Fun · 2026-10-30

Verbs can have an object →