Modal verbs are auxiliary verbs that change the meaning of a sentence: they show whether something is possible, allowed, necessary, advisable or likely. There are only a few of them, but they appear in almost every conversation and in practically every exam.Modal verbs são verbos auxiliares que mudam o sentido da frase: mostram se algo é possível, permitido, obrigatório, aconselhável ou provável. Eles são poucos, mas aparecem em quase toda conversa e em praticamente todas as provas.
A1 The golden rules and can
All modal verbs follow the same simple rules. Learn them once and they work for can, must, should and all the others.Todos os modais seguem as mesmas regras simples. Aprenda uma vez e elas valem para can, must, should e todos os outros.
The golden rules
1. After a modal, the verb stays in the base form, without to: She can swim. ✗ She can to swim.1. Depois do modal, o verbo fica na forma base, sem to: She can swim. ✗ She can to swim.
2. There is no -s in the third person: He must go. ✗ He musts go.2. Não há -s na terceira pessoa: He must go. ✗ He musts go.
3. Negatives and questions don’t use do/does: I can’t. / Can you? (The exception is have to, which is not a pure modal: Do you have to go?)3. Negativa e pergunta sem do/does: I can’t. / Can you? (A exceção é have to, que não é um modal puro: Do you have to go?)
4. Modals have no infinitive, no participle and no future form of their own. In these cases we use be able to and have to: I’ll be able to come. I’ll have to leave early.4. Os modais não têm infinitivo, particípio nem futuro próprio. Nesses casos usamos be able to e have to: I’ll be able to come. (Vou poder vir.) I’ll have to leave early. (Vou ter que sair cedo.)
Ability: can, could, be able to
Can means “saber” or “conseguir” in the present. Could is its past form. For other tenses, use be able to.Can significa “saber” ou “conseguir” no presente. Could é a forma no passado. Para os outros tempos, use be able to.
- Sarah can play the violin very well. (A Sarah sabe tocar violino muito bem.)
- I could swim when I was five. (Eu sabia nadar quando tinha cinco anos.)
- I’ll be able to help you tomorrow. (Vou poder te ajudar amanhã.)
- She hasn’t been able to sleep. (Ela não tem conseguido dormir.)
Permission and requests
To ask for permission, the modal you choose shows how polite or formal you are. Can is fine with friends; could and may sound more polite.Para pedir permissão, o modal escolhido mostra o quanto você está sendo educado ou formal. Can funciona bem com amigos; could e may soam mais educados.
| Request | Level | Português |
|---|---|---|
| Can I use your phone? | informal | Posso usar seu celular? |
| Could I use your phone? | polite | Eu poderia usar o seu celular? |
| May I use your phone? | formal | Posso usar o seu telefone, por gentileza? |
| Would you mind if I used your phone? | very polite | Você se importaria se eu usasse seu telefone? |
A2 The modals at a glance, obligation and advice
This table shows the main meanings of each modal. Notice that the same modal can have more than one meaning, so the context decides.Esta tabela mostra os principais sentidos de cada modal. Repare que o mesmo modal pode ter mais de um sentido, então é o contexto que decide.
| Modal | Meaning | Português | Example |
|---|---|---|---|
| can | ability, permission, possibility | poder, saber, conseguir | She can play the violin. |
| could | past ability, polite request, possibility | podia, conseguia, poderia | Could you help me? |
| may | permission (formal), possibility | poder, talvez | May I come in? |
| might | weaker possibility | talvez, pode ser que | It might rain later. |
| must | obligation, strong deduction | dever, ter que; deve ser | You must wear a seatbelt. |
| have to | obligation (from outside); uses do/does | ter que | I have to work on Saturday. |
| should | advice, opinion | deveria | You should see a doctor. |
| ought to | advice (less common) | deveria | You ought to apologise. |
| shall | offers and suggestions (British English) | (vamos?, quer que eu…?) | Shall I open the window? |
| would | polite requests, imagination | -ria (gostaria, faria) | Would you like some tea? |
Obligation: must and have to
must
An obligation that the speaker feels or imposes.Obrigação que o falante sente ou impõe.
I must call my mum. (Preciso ligar para a minha mãe: eu sinto que preciso.)
have to
An obligation that comes from outside (rules, the boss, the law).Obrigação que vem de fora (regras, chefe, lei).
I have to wear a uniform at work. (Tenho que usar uniforme no trabalho.)
In the past, both must and have to become had to: I had to work late yesterday.No passado, must e have to viram had to: I had to work late yesterday. (Tive que trabalhar até tarde ontem.)
Advice: should
- You should study more for the test. (Você deveria estudar mais para a prova.)
- You shouldn’t eat so much sugar. (Você não deveria comer tanto açúcar.)
- What should I wear to the interview? (O que eu deveria vestir para a entrevista?)
- Should we bring anything to the party? (A gente deveria levar alguma coisa para a festa?)
Offers and suggestions: shall
Shall is mostly British and appears in questions with I and we to offer help or make a suggestion.Shall é mais britânico e aparece em perguntas com I e we para oferecer ajuda ou fazer uma sugestão.
- Shall we go to the cinema tonight? (Vamos ao cinema hoje à noite?)
- Shall I carry your bag? (Quer que eu carregue a sua bolsa?)
B1 Possibility, prohibition and ought to
Possibility: may, might, could
To say that something is possible but not certain, use may, might or could + base verb. In Portuguese we often say “talvez” or “pode ser que”.Para dizer que algo é possível, mas não certo, use may, might ou could + verbo na forma base. Em português costumamos dizer “talvez” ou “pode ser que”.
- It may rain this evening. (Pode chover hoje à noite.)
- She might be at home. (Talvez ela esteja em casa.)
- That could be the answer. (Essa pode ser a resposta.)
- He might not come today. He’s sick. (Talvez ele não venha hoje. Ele está doente.)
Degrees of certainty
will (certain) > should (expected) > may (possible) > might / could (less likely).will (certeza) > should (esperado) > may (possível) > might / could (menos provável).
Mustn’t or don’t have to?
In the affirmative, must and have to are similar. In the negative, they mean completely different things.Na afirmativa, must e have to são parecidos. Na negativa, significam coisas completamente diferentes.
mustn’t = prohibited
It is not allowed.É proibido.
You mustn’t smoke here. (Você não pode fumar aqui.)
don’t have to = not necessary
It isn’t necessary, but you can if you want.Não é necessário, mas você pode, se quiser.
You don’t have to come. (Você não precisa vir.)
Advice: ought to
Ought to means the same as should, but it is much less common. Notice that it keeps to.Ought to significa o mesmo que should, mas é bem menos comum. Repare que ele mantém o to.
- You ought to apologise. (Você deveria pedir desculpas.)
- We ought to leave now, or we’ll miss the bus. (A gente deveria sair agora, senão vamos perder o ônibus.)
B2 Deduction: must, can’t, might
Modals also show how sure we are about something, in the present and in the past. For the past, use modal + have + past participle.Os modais também mostram o quanto temos certeza de algo, no presente e no passado. Para o passado, use modal + have + particípio.
| Meaning | Present | Past (modal + have + participle) | Português |
|---|---|---|---|
| almost certain: yes | She must be tired. | She must have been tired. | quase certeza que sim |
| maybe | She might / may be at home. | She might have left early. | talvez |
| almost certain: no | That can’t be true. | He can’t have seen us. | quase certeza que não |
| advice / criticism | You should study. | You should have studied. | conselho / crítica (devia ter estudado) |
- He must have been tired after studying all day. (Ele devia estar cansado depois de estudar o dia todo.)
- Bob may have told Jessy the truth. (Talvez o Bob tenha contado a verdade para a Jessy.)
- He shouldn’t have done that. (Ele não deveria ter feito isso.)
- You can’t have finished already! (Não é possível que você já tenha terminado!)
Exam tip
Entrance exams love to ask what a modal “expresses”. Learn the labels in English: ability (can), permission (may, can), possibility (may, might, could), obligation or necessity (must, have to), advice (should, ought to) and deduction (must, can’t).Os vestibulares adoram perguntar o que um modal “expressa”. Aprenda os rótulos em inglês: ability (habilidade: can), permission (permissão: may, can), possibility (possibilidade: may, might, could), obligation ou necessity (obrigação ou necessidade: must, have to), advice (conselho: should, ought to) e deduction (dedução: must, can’t).
Common mistakes
Avoid these
✗ She can to swim. ✓ She can swim.Depois de modal, verbo sem to.
✗ He musts go. ✓ He must go.Modais não levam -s na terceira pessoa.
✗ Do you can help me? ✓ Can you help me?Modais fazem a pergunta sozinhos, sem do/does.
✗ I will can come. ✓ I will be able to come.No futuro, use be able to.
✗ You mustn’t come if you’re busy. ✓ You don’t have to come if you’re busy.“Não precisa” é don’t have to; mustn’t é proibição.
✗ He should have do it. ✓ He should have done it.Depois de have, use o particípio.
Quick summary
| Use | Example | Português |
|---|---|---|
| ability | I can speak three languages. | Eu sei falar três idiomas. |
| permission | May I sit here? | Posso me sentar aqui? |
| possibility | It might snow tonight. | Talvez neve hoje à noite. |
| obligation | I have to wake up at six. | Tenho que acordar às seis. |
| prohibition | You mustn’t park here. | Você não pode estacionar aqui. |
| no obligation | You don’t have to pay. | Você não precisa pagar. |
| advice | You should rest. | Você deveria descansar. |
| suggestion | Shall we start? | Vamos começar? |
| deduction (past) | They must have forgotten. | Eles devem ter esquecido. |
Practice time
Quiz