How to make negatives with be and can
Short answer: To say no with am, is, are or can, add not after the verb: I am not, she is not (isn’t), they are not (aren’t), he cannot (can’t). After can’t, use the plain action word. Do not use don’t with am, is and are: say She isn’t happy, not She don’t happy.
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At a glance
| Subject | Negative | Short form |
|---|---|---|
| I | am not | I’m not |
| he, she, it | is not | isn’t |
| we, you, they | are not | aren’t |
| can | cannot | can’t + plain verb |
In short
- Add not after am, is, are: am not, isn't, aren't.
- cannot → can't, then the plain action word.
- Do not use don't with am, is and are.
What is the rule for “Negatives: not with be and can”?
The rule
Put not after am, is or are. cannot becomes can't.
How it looks
I am not · he / she / it is not (isn't) · we / you / they are not (aren't) · can't + action word
What it means
not says that something is not true.
When to use it
Say what is not true or what you cannot do.
How it works
- Keep the verb be (am, is, are) and add not after it.
- For can, use can’t or cannot and then the plain verb: He can’t swim.
- Use the short forms in speaking: isn’t, aren’t, can’t. The full forms are fine in writing.
- Do not use don’t or doesn’t with be: She is not tired.
Examples of “Negatives: not with be and can”
- I am not hungry.
am + not. - He isn't at school.
isn't = is not. - We aren't late.
aren't = are not. - A fish can't walk.
can't + the plain action word. - I’m not ready.
I’m not is the usual short form of I am not. - It isn’t cold today.
isn’t = is not. - They aren’t at home.
aren’t = are not. - He can’t play today.
can’t + play, the plain verb.
Common mistakes with “Negatives: not with be and can”
She not happy.→ She isn't happy.
Keep is and add not.I not hungry.→ I am not hungry.
Keep am and add not.She don't happy.→ She isn't happy.
don't is for action words. With happy we use isn't.They not are here.→ They are not here.
not goes after are.He cannot swims.→ He cannot swim.
After cannot, use the plain verb.
Exceptions: watch out
- I'm not
With I we say I'm not or I am not. We do not say I amn't.
Negatives with be and negatives with don’t
Use not after be (am, is, are) and can. Use don’t or doesn’t with action verbs.
| Verb | Negative | Example |
|---|---|---|
| be | am / is / are + not | She isn’t tired. |
| can | can’t + plain verb | I can’t swim. |
| action verb | don’t / doesn’t + plain verb | I don’t like fish. |
See also: Negatives: don't and doesn't
Check yourself
- Make it negative: “She is happy.”
Show the answer
She isn’t happy. is + not = isn’t.
- Make it negative: “We are late.”
Show the answer
We aren’t late. are + not = aren’t.
- Make it negative: “I can swim.”
Show the answer
I can’t swim. can’t + the plain verb.
How to practice “Negatives: not with be and can”
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: Negatives: not with be and can
Questions
Why do we say “I’m not” and not “I amn’t”?
English does not use amn’t. I’m not and I am not are the two correct ways.
Is “cannot” one word or two?
One word: cannot. Can not is rare and used for emphasis.
Can I say “She don’t happy”?
No. Don’t is for action verbs. With happy, the verb is be: She isn’t happy.
More Sentence Building rules
- Subject + Verb: A sentence needs someone or something (the subject) and a verb: Birds fly.
- 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: 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
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