Modal verb
The modal verb can
can · never changes
A1Meaning: to be able to; to be allowed to · Type: modal
Key points to remember
- Modal verb of ability and permission:
cannever changes - Same form for everyone:
I/you/he/she/we/they can(never cans) - Past:
could - Negative:
cannotorcan't
Conjugation of the modal verb can
Modal verbs never change: the same form for I / you / he / she / it / we / they, no -s in the 3rd person, and no to before the next verb.
Affirmative
subject + can + base form
- I can swim.
- She can speak three languages.
Negative
subject + cannot / can't
- I can't drive.
- He cannot come tomorrow.
Question
can + subject + base form?
- Can you help me?
- Can she swim?
In the past: could. The full negative is written as one word: cannot.
How to use can
1. Talking about what you are able to do
- I can swim.
- She can speak three languages.
2. Asking for or giving permission
Can I…? asks if something is allowed. In British English, people usually say the toilet rather than the bathroom.
- Can I go to the bathroom?
- You can leave now.
3. Asking someone to do something
Can you…? asks someone to do something for you. Could you…? is more polite.
- Can you help me?
- Can you open the window?
4. Talking about a possibility
It can be… means it is sometimes true.
- It can be cold in winter.
Common mistakes to avoid
1. I can to swim ❌
After a modal verb, use the base form with no to: I can swim ✓ / I can to swim ✗.
2. She cans ❌
Modal verbs never change: She can, not She cans. It is the same for will, must, may and should.
3. Can not ❌
The full negative is written as one word: cannot. The short form is can't.
Going further
Conjugating to can is a key skill in the English contest
Every year, the Big Challenge tests the key English verbs. Register your students so they can check their level in a real contest.
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Practise on PLAYYou can conjugate to can. Now say it out loud.
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For teachersReady-made activities to practise to can in class
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Related pages: can
Pages on a similar topic or with a similar use, so you can keep exploring.
Frequently asked questions
How do you use can in English?+
Can is a modal verb (a helper verb that goes before another verb). It shows ability (I can swim), permission (Can I leave now?) or possibility. After can, use the base form of the verb (with no ending), and no to.
What is the past tense of can?+
The past of can is could: I could swim when I was 5. Could is also used for a possibility or an offer:I could help you with your homework.
How do you make can negative and ask a question?+
Negative: cannot (or can't, the short form): I can't swim. Question: put can before the subject: Can you swim? You don't need do.
What is the difference between can and could?+
Can is for the present: I can swim. Could is for the past (I could swim when I was 5) or for a more polite question: Could you help me? is more polite than Can you help me?
What is the difference between can and be able to?+
Can is shorter and more common. Use be able to when can is not possible, for example in the future or in the Present Perfect: I will be able to come, never I will can come. In the present, I can and I am able to mean the same.
Updated on 12 November 2026 by the Big Challenge teaching team. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999. Our teaching approach →
The Big Challenge · Updated on 12 November 2026 · Source: www.thebigchallenge.com/bl/academy/learn-english/verbs/can
© The Big Challenge. Copying allowed for classroom use. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999.