1. Can shows ability
Use can before an action verb to describe a skill or say that someone is able to do something. It can mean knowing how to do an action, as well as being able to perform it.
The ability can be a learned skill, a physical capacity or something possible in a particular situation. Can does not promise that the person will actually perform the action.
subject + can + action verb
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
I can make soup.
I can make soup.
The speaker describes a cooking skill rather than ordering soup.
We can carry this box together.
We can carry this box together.
Two people have the ability to handle this particular box together.
2. One form with I, she, they and other subjects
Modal can takes no -s with he, she or it. The main verb after it also takes its base form: she can read, not reads.
Do not add am, is or are before can. A short description of a skill needs only the subject, can and an action verb.
I / you / he / she / it / we / they + can + read
My brother can draw.
My brother can draw.
Both can and draw remain without -s, although the subject names one person.
These birds can fly.
These birds can fly.
The plural subject does not change can.
3. After can: a verb without to or -ing
The base form is swim, write, use or make. Use this form after can: can swim, can write. Do not add to before it or replace it with swimming. A modifier can appear between can and the verb: We can both swim.
To can occur later if it belongs to another part of the sentence: can walk to work. Walk already has the right form after can; to work identifies the destination.
can + swim / write / use / make
She can use this computer.
She can use this computer.
Can is followed by use without to.
He can walk to work.
He can walk to work.
To expresses direction after walk; this is not the incorrect can to walk.
4. Ability differs from doing something now or having permission
I can dance describes an ability. I am dancing describes an action happening now. Both sentences are correct but answer different questions. Can dance alone does not prove that the speaker is dancing now.
Can also expresses permission and requests. Identify the meaning from the situation: a skills check, a room rule or a request to act. The presence of can alone does not reliably establish which meaning is intended.
I can swim, but I am at home now.
I can swim, but I am at home now.
The skill is compatible with being at home. Can alone says nothing about whether the person is swimming now.
The teacher says we can use our phones.
The teacher says we can use our phones.
In this context, the teacher gives permission rather than checking technical ability.
Can you read this small text without glasses?
Can you read this small text without glasses?
In an eyesight check, this asks about ability. In another context, a similar question could be a request.
5. Ask about a skill and give a short answer
In an ordinary yes/no question, place can before the subject. This modal question needs no do or does. The action verb keeps its base form.
A short answer repeats can: Yes, I can. There is no need to repeat the whole action if it is understood. When a question addresses you, use I in the answer about yourself.
Can + subject + verb? → Yes, I can. / No, I can’t.
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
Can your friend play chess?
Can your friend play chess?
Can comes before your friend; play stays unchanged.
Yes, she can.
Yes, she can.
The action is understood from the preceding question, so it need not be repeated.
6. A brief contrast: can and can’t
Can affirms ability; can’t or cannot denies it. In an ordinary negative, write the full form as one word: cannot. Can’t is a common contraction; both forms can describe a missing skill.
Do not add don’t or doesn’t before modal can. “Cannot” does not always mean permanent inability: I can’t read this without glasses can describe current conditions only. Detailed practice of negatives belongs to a separate topic.
subject + can’t / cannot + verb
- subject / S —
- The grammatical subject: who or what the clause is about; the verb agrees with it. In The book was written, the book is the subject, although someone else does the action.
- verb / V —
- A word for an action or state, such as work or be. The pattern determines its form.
I can read English, but I can’t read this small print.
I can read English, but I can’t read this small print.
The general skill exists, but the particular text cannot currently be read.
Our cat cannot open this door.
Our cat cannot open this door.
Cannot denies the ability to open this particular door.
7. Scope of the rule and your own statement
To describe yourself, choose an action you really can do, or imagine being able to do, and add one useful detail: a language, an object, a place or a degree of skill. You do not need to disclose personal circumstances; a fictional character works too.
The unchanging-form rule concerns modal can meaning “be able to”. There is a separate lexical verb can meaning “preserve in cans”: He cans food. It is an ordinary verb and can take -s; it is not an exception to modal can.
This lesson practises present ability. Past skills and more complex be able to constructions are studied separately; this does not mean can can never refer to future circumstances.
I can write short emails in English.
I can write short emails in English.
The detail short emails makes the skill description specific.
He cans food.
He cans food.
Cans here means preserving food, rather than ability. Do not transfer this form to He can cook.
Common mistakes
Incorrect:She cans drive a car.
Correct:She can drive a car.
For ability, can is an unchanging modal verb; she adds no -s to it.
Incorrect:He can to ride a bike.
Correct:He can ride a bike.
Directly after modal can, use base-form ride without to.
Incorrect:I can swimming.
Correct:I can swim.
Swimming cannot stand alone after can in this skill statement; use swim.
Incorrect:Does she can cook?
Correct:Can she cook?
For an ordinary modal question, move can before the subject rather than adding does.
Incorrect:We don't can read this.
Correct:We can't read this.
Negate modal can with can’t or cannot, without don’t.