Mastering Can, Could, May, Might: B1 Modal Verbs for Ability & Possibility — B1 English grammar lesson by Langcom

Mastering Can, Could, May, Might: B1 Modal Verbs for Ability & Possibility

Raúl Maguiña

Fundador de Langcom | Examinador de Cambridge y del SIELE

septiembre 26, 2026

B1✏️ Gramática⏱️ 7 minutos de lectura📅 Actualizado en septiembre de 2026
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Modal verbs can, could, may, y might are essential for expressing ability, possibility, and permission in English. These special verbs always come before a main verb in its base form, without “to.” For example, we say I can swim, no I can to swim. A key rule is that these modals never change their form; you don’t add -s para he/she/it o -ed for the past. Can y could primarily describe ability: can for the present and could for the past. On the other hand, may, might, y could are used to talk about possibilities in the present or future. Mastering these distinctions will significantly improve your B1 English communication skills.

What Are Modal Verbs?

Modal verbs are a special type of auxiliary (helping) verb. They add extra meaning to the main verb in a sentence.

They express ideas like possibility, ability, permission, obligation, and advice. In this lesson, we focus on can, could, may, y might.

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How to Talk About Ability with Can y Could?

Utilizamos can to talk about ability in the present. It means "to be able to do something."

  • Anna can speak French. (She has the ability now.)
  • I can swim very well. (I have this skill.)

For inability in the present, we use can't (o cannot).

  • She can't speak Chinese. (She doesn't have this ability.)
  • I can't hear you. (I am unable to hear you now.)

To talk about ability in the past, we use could.

  • Max could walk when he was one year old. (He had this ability in the past.)
  • When I was younger, I could run very fast. (I had this ability then.)

For inability in the past, we use couldn't (o could not).

  • He couldn't talk until he was two. (He didn't have this ability until then.)
  • I couldn't find my keys yesterday. (I was unable to find them.)

To ask questions about ability, we put can o could before the subject.

  • Can Anna speak French?
  • Could Max walk when he was one?

How to Express Possibility with May, Might, y Could?

Utilizamos may, might, y could to talk about things that are possible in the present or future.

  • It might be very hot tomorrow. (There is a possibility.)
  • We may go swimming this afternoon. (It's possible we will go.)
  • There could be a storm later this evening. (A storm is possible.)

May y might are very similar when expressing possibility. Might often suggests a slightly lower chance of something happening.

It is important NOT to use can for specific future possibilities. For example, do not say It can rain tomorrow if you mean it's possible it will rain. Use It might rain tomorrow instead.

For negative possibilities, we use may not o might not.

  • Laura is not feeling well, so she may not go to school today. (It's possible she won't go.)
  • You might not win the lottery this week. (It's possible you won't win.)

We do not use can't o couldn't for negative possibility in this way. Can't usually means inability or impossibility.

Note: The short form mightn't is very rare. Mayn't is not used at all.

Asking for Permission: May I o Could I?

When you want to ask for permission politely, you can use May I...? o Could I...?

  • May I sit here? (A polite way to ask for permission.)
  • Could I borrow your pen for a moment? (Also polite, slightly less formal than May I.)

Can I...? is also used for permission, but it is less formal than May I...? o Could I...?

  • Can I go to the party tonight? (Common in informal situations.)

Key Rules for Modal Verbs

Remember these important rules for all modal verbs:

  • No -s o -ed: Modal verbs never change their form. You cannot say He cans o They mighted.
  • Base Form Verb: They are always followed by the base form of another verb (the infinitive without to). Por ejemplo, She may come, no She may to come.
  • No to before: You don't use to before a modal verb. For example, I want to be able to swim (using 'be able to' as a substitute), not I want to can swim.
Summary of Modal Verbs: <span data-no-translation>Can</span>, <span data-no-translation>Could</span>, <span data-no-translation>May</span>, <span data-no-translation>Might</span>
Modal Verb Main Uses Ejemplo
Can Present ability; informal permission; general possibility I can speak English. Can I sit here?
Could Past ability; polite permission; present/future possibility I could swim when I was five. Could I help you? It could rain.
May Present/future possibility (stronger); formal permission She may be late. May I come in?
Might Present/future possibility (weaker/more uncertain) He might call later. We might not go.

Ejemplos

  • My brother can play the guitar very well.
  • When I was a child, I couldn't reach the top shelf.
  • It may rain later, so take an umbrella.
  • They might be at home, but I'm not sure.
  • Could you please help me with this box?
  • May I open the window? It's a bit warm in here.
  • I can't understand what he's saying.
  • She could speak three languages by the age of ten.
  • We might not finish the project on time.
  • The train could be delayed due to the snow.

Práctica

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Errores habituales de los hispanohablantes

Spanish speakers often make these mistakes when using can, could, may, y might:

  • Uso de can for future possibility: In Spanish, "poder" can mean both ability and possibility for the future. In English, use may, might, o could for specific future possibilities.
    • Incorrecto: It can snow tomorrow.
    • Correcto: It might snow tomorrow.
  • Añadir to after the modal verb: Remember that modal verbs are followed by the base form of the verb without to.
    • Incorrecto: I can to speak English.
    • Correcto: I can speak English.
  • Changing the modal verb form: Modal verbs never change. Do not add -s, -ed, o -ing.
    • Incorrecto: He cans play football.
    • Correcto: He can play football.
  • Uso de can't for negative possibility: For "it's possible it won't happen," use may not o might not. Can't usually means impossibility or inability.
    • Incorrecto: She can't come to the party, maybe.
    • Correcto: She might not come to the party.

Preguntas más frecuentes

What is the main difference between can y could?

Can is used for present ability (e.g., I can run fast now), while could is used for past ability (e.g., I could run fast when I was young). Could can also express possibility or polite permission in the present/future.

When should I use may en lugar de might?

Ambos may y might express possibility. May often suggests a slightly higher chance of something happening, or it can be more formal. Might suggests a weaker or more uncertain possibility. For example, It may rain (50% chance) vs. It might rain (30% chance).

¿Puedo usar can for possibility?

Yes, but usually only for general possibilities or things that are sometimes true (e.g., It can get very cold here in winter). For specific possibilities in the present or future, use may, might, o could (e.no-translation>It might be cold tomorrow).

How can understanding these modals help me with the B1 Preliminary exam?

Mastering can, could, may, y might is crucial for the B1 Preliminary exam, especially in the Speaking and Writing parts. You'll need to express your abilities, talk about future plans and possibilities, and ask for permission clearly and correctly. For example, in Speaking Part 2, you might describe what you can o can't do in a picture, or suggest what you could do in a given situation.

Sobre el autor: Raúl Maguiña

Raúl Maguiña es el director de la Asociación Educativa Langcom, un centro autorizado de preparación para el examen Cambridge English en tu país. Con más de una década de experiencia en la enseñanza de idiomas y la certificación internacional, ha ayudado a miles de estudiantes, profesores e instituciones educativas de 25 países a conseguir las certificaciones de inglés de Cambridge, IELTS, TOEFL y Michigan.

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