Mastering Can and Can’t: Expressing Ability in English (A2)

Raúl Maguiña

Fundador da Langcom | Examinador dos exames de Cambridge e SIELE

agosto 2, 2026

A2✏️ Gramática⏱️ 5 min de leitura
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To talk about what you are able to do now, use can. To talk about what you are not able to do now, use can’t. These words are modal verbs. They help us express present ability. For example, if you say I can speak English, it means you have the skill or knowledge to speak English. If you say I can’t swim, it means you do not have the ability to swim. The structure is simple: Subject + can/can’t + the base form of the verb. This means the verb after can ou can’t never changes its form, even for ‘he’ or ‘she’. This makes it very easy to use for all subjects (I, you, he, she, it, we, they). You will use can e can’t often in daily conversations to describe your skills and capabilities.

What is ‘Can’ for Present Ability?

Can is a modal verb. We use it to show that someone has the skill, knowledge, or possibility to do something in the present.

  • It tells us what is possible or what someone is capable of doing right now.
  • The structure is always Subject + can + the base form of the verb.

For example:

  • I can play the guitar. (This means I have the skill to play it.)
  • She can run very fast. (This means she has the physical ability.)

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How Do We Use 'Can't' for Inability?

Can't is the negative form of can. It is short for cannot.

  • Utilizamos can't to show that someone does não have the skill, knowledge, or possibility to do something in the present.
  • The structure is Subject + can't + the base form of the verb.

For example:

  • He can't cook well. (He does not have the skill to cook well.)
  • We can't meet tomorrow. (It is not possible for us to meet.)

Asking Questions with 'Can'

To ask about someone's ability or if something is possible, we put Can at the beginning of the question.

  • The structure is Can + Subject + the base form of the verb?
  • For short answers, we use Yes, + Subject + can. ou No, + Subject + can't.

For example:

  • Can you swim? Yes, I can. (I have the ability.)
  • Can she speak French? No, she can't. (She does not have the skill.)

What About Past Ability? ('Could' and 'Couldn't')

While can e can't are for present ability, we use could e couldn't for past ability.

  • Could means 'was able to' or 'had the ability to' in the past.
  • Couldn't means 'was not able to' or 'did not have the ability to' in the past.

For example:

  • When I was young, I could climb trees. (I had the ability in the past.)
  • My grandfather couldn't use a computer. (He did not have the ability in the past.)

Key Rules for Using 'Can' and 'Can't'

Can e can't are special verbs called modal verbs. They follow simple rules:

  • No 'to' after can/can't: Always use the base form of the verb without to.
    Correto: I can play.
    Incorreto: I can to play.
  • No '-s' for 'he/she/it': Can does not change its form for any subject.
    Correto: He can sing.
    Incorreto: He cans sing.
  • No 'do/does' in questions or negatives: Do not use auxiliary verbs do ou does with can.
    Correto: Can you help?
    Incorreto: Do you can help?
Structure of 'Can' and 'Can't' for Present Ability
Formulário Structure Example
Positive Subject + can + Base Verb I can sing.
Negative Subject + can't + Base Verb She can't dance.
Question Can + Subject + Base Verb? Can you swim?

Exemplos

  • My brother can speak three languages fluently.
  • I can't drive a car yet, but I'm learning.
  • Can you help me with this heavy box?
  • She can play the piano beautifully.
  • We can't come to the party tonight.
  • The baby can walk now!
  • They can't hear you from here.
  • Can I borrow your pen for a moment?

Prática

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Erros comuns entre falantes de espanhol

Spanish speakers sometimes make specific mistakes with can e can't:

  • Adding 'to' after can: In Spanish, you might use 'poder + infinitive', but in English, can is directly followed by the base verb.
    Incorreto: I can to swim.
    Correto: I can swim.
  • Using 'do/does' in questions: Can is a modal verb, so it forms questions by itself.
    Incorreto: Do you can speak English?
    Correto: Can you speak English?
  • Changing 'can' for 'he/she/it': Remember, can never changes its form.
    Incorreto: She cans play tennis.
    Correto: She can play tennis.

Perguntas frequentes

What is 'can' used for in English?

Can is used to express present ability, possibility, or permission. For example, I can sing means you have the skill to sing.

How do I make 'can' negative?

To make can negative, you use can't (short for cannot). For example, I can't swim means you are not able to swim.

Is 'can' a regular verb?

No, can is a modal verb. This means it has special rules: it doesn't change form for different subjects (like he cans), and it's always followed by the base form of another verb without to.

How is 'can' used in the A2 Key (KET) exam?

In the A2 Key exam, you might see can e can't in reading tasks (e.g., understanding descriptions of abilities) or listening tasks (e.g., identifying what someone can or can't do). You may also need to use it correctly in writing tasks, such as describing yourself or others.

What is the difference between 'can' and 'could'?

Can is used for present ability (what you are able to do now), while could is used for past ability (what you were able to do in the past). For example, I can speak English (now) vs. When I was five, I could ride a bike (in the past).

Aulas relacionadas

Sobre o autor: Raúl Maguiña

Raúl Maguiña é diretor da Asociación Educativa Langcom, um centro autorizado de preparação para o Cambridge English em Argentina. Com mais de uma década de experiência no ensino de idiomas e em certificações internacionais, ele já ajudou milhares de alunos, professores e instituições de ensino em 25 países a obter as certificações de inglês da Cambridge, IELTS, TOEFL e Michigan.

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