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Revision [3/3]

hi folks,

Today, i will finish this revision with the subjects: [NO] OBLIGATION / PROHIBITION / ADVICE OR OPINION (with must, have to and should), DEDUCTION (with must, may, might, can´t) and ABILITY / POSSIBILITY.


Must and have to a very similar meaning. Have to is more common for general, exernal obligations, for exemple rules and laws. Must is more common for specific (i.e. on one occasion) or personal obligations.
I have to wear a shirt and tie at work (it´s the rule in this company)
I must buy a new shirt (it´s my own decision)
Have to is a normal verb and it exists in all tenses
Must is a modal verb. The only forms are must and mustn´t.
– You can also use have to or must for strong recommendations.


You don´t have to pay for the tickets. They´re free.
You don´t have to go to the party if you don´t want to.


Don´t have to and mustn´t are completely different.
You musn´t drive along this street (It´s prohibited, agains the law).
You don´t have to drive (You can drive if you want to but it´s not necessary / obligatory)
– You can often use can´t or not allowed to instead of mustn´t
Have got to is often used instead of have to in spoken english.


Should is not as strong as must / have to. We use it to say if we think something is the right or wrong thing to do.
Should is a modal verb. The only forms are should and shouldn´t.
– You can also use ought to and ought not to instead of should / shouldn´t.
You should take warm clothes with you to Dublin. It might be cold at night.


– We often use must, may / might, can´t to say how sure or certain we are about something.
– In this context, the opposite of must is can´t NOT mustn´t.

When you are sure something is true: MUST
They must be out. There aren´t any lights on.

When you think something is possibly true: MAY or MIGHT
She´s not at home. She may be working.
She might not like that skirt. It´s not her style.

When you are sure something is impossible / not true: CAN´T
He can´t be ill. I saw him at the gym.


This subject is too simple.
When the phase was in past tense, you MUST use COULD
When the phase was in present tense, you MUST use CAN!
When the phase was in future tense, you MUST use BE ABLE TO

¹Also, you SHOULD use COULD in questions.
²Next to BE ABLE TO, you HAVE TO put the verb in a infinitive way.

A hug for everyone!



fevereiro 10, 2009 - Posted by | English | , , , , , , ,

1 Comentário »

  1. Eu gosteei muito desta explicação e dos exemplos que traz o texto ! Muito bom mesmo.. eu conseguii entender tudo com os bons exemplos citados ! Obrigado mesmo Marco Rosner ! Thank you !

    Comentário por Bianca .M. | novembro 28, 2010

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