Can and can’t: how to talk about ability
Short answer: Can means someone is able to do something. Can’t, or cannot, means someone is not able to. After can, use the plain action word with no -s and no to: She can sing. For a question, put Can first: Can you jump? Answer: Yes, I can. or No, I can’t.
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At a glance
| Use | Pattern | Example |
|---|---|---|
| able to | someone + can + action word | She can sing. |
| not able to | someone + can’t + action word | A cow can’t fly. |
| question | Can + someone + action word? | Can you jump? |
| short answer | Yes, I can. / No, I can’t. | Yes, I can. |
In short
- can + plain action word: I can swim.
- No -s and no to after can.
- Questions start with Can: Can you jump?
What is the rule for “can and can't”?
The rule
can tells what someone is able to do. can't means cannot.
How it looks
someone + can / can't + action word (no -s, no to)
What it means
can = able to. can't = not able to.
When to use it
Use it for people and animals. Start a question with Can.
How it works
- Put can between the subject and the action word: I can swim.
- The action word stays plain. No -s (not He can runs) and no to (not I can to swim).
- can’t is the short form of cannot. Write cannot as one word.
- To ask, put Can before the subject: Can you help me? Use can to ask politely too: Can I sit here?
Examples of “can and can't”
- She can sing.
can + sing. No -s on can. - Birds can fly.
Many birds, still can + fly. - A cow can't fly.
can't means cannot. - Can you jump?
A question starts with Can. Answer: Yes, I can. / No, I can't. - I can ride a bike.
can + ride, the plain form. - My dog can’t swim.
can’t tells us the dog is not able to swim. - Can I ask a question?
Can also asks for permission. - We can see the sea from here.
can often goes with see, hear and feel.
Common mistakes with “can and can't”
He can runs.→ He can run.
After can we use the plain action word: run.I can to swim.→ I can swim.
Do not put to after can.He cans run.→ He can run.
can never takes -s.Can he plays the guitar?→ Can he play the guitar?
After can, use the plain action word: play.She cans sing.→ She can sing.
can never changes: no -s, no -ed.
Exceptions: watch out
- can't = cannot
can't is the short form of cannot. It is written as one word: cannot.
Can, can’t and cannot
These three forms are used in different places. In speech and informal writing, can’t is normal. In formal writing, cannot is better.
| Form | Use | Example |
|---|---|---|
| can | able to | I can read. |
| can’t | not able to (short form) | I can’t read that. |
| cannot | not able to (formal, one word) | I cannot attend the meeting. |
See also: Negatives: not with be and can
Check yourself
- Fill the gap: “She can ___.” (sing / sings)
Show the answer
sing After can use the plain action word.
- Which is correct: “He can to run” or “He can run”?
Show the answer
He can run. Do not put to after can.
- How do you ask: “Are you able to swim?” with can?
Show the answer
Can you swim? A question starts with Can.
How to practice “can and can't”
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: can and can't
Questions
Is “can” only about ability?
No. Can also asks for or gives permission (Can I go?) and makes polite requests (Can you help me?).
Why is there no -s in “She can sing”?
Can is a special helping verb. It never changes, so there is no -s for he, she or it.
What is the past of “can”?
For ability, could: When I was five, I could swim. Be careful: could is a different word in meaning and use, and you will study it later.
More Grammar Foundations rules
- Naming words: nouns: A noun is a naming word. It names a person, an animal, a place or a thing.
- A or An?: Before one thing, say a or an. Choose by the first sound.
- One and many: plural -s: For more than one thing, add -s: one cat, two cats.
- Plurals: -es, -ies and special nouns: Most nouns add -s. Some add -es or -ies, and some change a lot.
- this, that, these, those: Use this and these for things near you. Use that and those for things far away.
- I am, you are, it is: Use am with I, are with you and is with it.
Used in these writing topics
Part of the 📘 Grammar tool. Level G1: Grammar Foundations. 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