In English we use should / shouldn't /ought to / oughtn't to give advice. We use should / ought to to say something is a good thing to do and shouldn't / oughtn't to say something is a bad thing to do.
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Note : To ask for advice we can say: What should I do?
In English, "can" is a modal verb and only has a present, past and conditional form. It can also be used with a future meaning.
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Note : Can is not used to talk about specific possibilities.
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In English, could is used to talk about past ability/ permission/ possibility.
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"Be able to" can be used in the present, past, future, present perfect and as a gerund or infinitive.
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Note : be able to in the present and past is more formal than can or could.
In English we use might or may to say something in the future is possible, but not decided.
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To make questions with might we usually use Do you think...?
Example questions :
In English we can also use might in short answers.
Example short answers :
In English we use have to + infinitive to say something is necessary or obligatory. We normally use have to for a general obligation from an outside source, such as work or the law.
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In English we use don't have to + infinitive to say something is not necessary or obligatory. It means you can if you want to, but it's not necessary.
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To make questions we use do/does.
Example questions :
Form : ( Must + infinitive without to )
In English we use must + infinitive to talk about rules and obligations. We normally use must when the speaker imposes the obligation, such as a teacher to students, or even to yourself.
Form : ( Mustn't + infinitive without to )
In English we use mustn't + infinitive to say something is prohibited.
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Note : You can often use can't or be + not allowed to instead of mustn't.
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Note : Mustn't and don't have to have completely different meanings.
Mustn't Vs Don't Have To
Note : Have to is a normal verb and exists in all tenses whereas must is a modal verb and its only forms are must and mustn't.
You can also use have to and must for strong recommendations.
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In English we use must when we are sure something is true.
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In English we use may or might when we think something is possibly true.
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In English we use can't when we are sure something is impossible.
Examples sentences :
Note : In this context, the opposite of must is can't, NOT mustn't!
In the past, can't, could, may, might and must for probability change to can't have, could have, may have, might have and must have + past participle (Verb 3).
In the past, should and ought to change to should have and ought to have + past participle (Verb 3).
Note : the form of "must" for obligation and "can" are exceptions.
Must for obligation changes to had to + infinitive
Can changes to could or was able to
Modal example sentences | |
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Can you please stop being stupid, dear? | Querido, pode parar de ser estúpido, por favor? |
By just paying a little bit more you could've rented a house in better condition. | Pagando um pouco mais, você poderia ter alugado uma casa em melhor estado. |
Can you open the tube map for me? | Pode abrir o mapa do metrô para mim? |
Have you watched A.I.? It's quite violent, too, you might like it. | Você já viu o Inteligência Artificial? É bastante violento também, você deve gostar. |
Mike, can you hear me? | Mike, consegue me ouvir? |
I don't want to upset you, but I have to tell you something! | Eu não quero aborrecer você, mas eu tenho de contar uma cosa para você! |
We can use matches... Or a lighter! | Podemos usar fósforos... Ou um isqueiro! |
Maybe you can try some prawn crackers. | Pode experimentar as chips de camarão. |
The burglar might like it. | O ladrão pode gostar delas. |
Umm... I'm sorry, but I can't find a booking in that name. | Hum... Lamento, mas não encontro nenhuma reserva com esse nome. |
No, you have to bring your own or buy new ones, dear. | Não, você terá de trazer os seus ou comprar novos, querida. |
I brought one, maybe you should bring one, too. | Eu trouxe, talvez você também deva trazer. |
Since I can't smoke in the room, I have to go to the garden. | Já que não posso fumar no quarto, tenho de ir para o jardim. |
I have to go home and check on Pogo first. | Primeiro, tenho de ir a casa ver como está o Pogo. |
Cate, my queue is going faster, you can come over here. | Cate, minha fila está indo mais rápido, você pode vir para aqui. |
We can get the other things on the way back. | Podemos pegar as outras coisas no regresso. |
You could have brought the book directly! | Podia ter trazido o livro! |
You shouldn't have woken her up in the morning! | Você não a devia ter acordado de manhã! |
Check the cupboard just in front of you, it should be there. | Procure no guarda-loiça na sua frente, deve estar lá. |
It's a very long time, who could stand it? | É muito tempo, quem aguenta isso? |