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Modal Auxiliary Verbs (MAV) IES Diego Torrente Pérez – San Clemente

Remember that…     

MAV do not add –s to the 3rd person singular in the Present Simple. MAV do not usually have past forms but can be used with Perfect Infinitives to talk about the past MAV are followed by bare infinitive MAV haven’t got infinitives or –ing forms Since they are auxiliary verbs, the do not need do, will, did or any other auxiliary

How can we express obligation and advice? MUST It expresses an obligation that comes from the speaker’s opinion. It is associated with a formal written style

MUSTN’T means PROHIBITION (=can´t)



It expresses an obligation that is based on the authority of another person or on laws. It appears more often than must. It is a semi-modal DON’T HAVE TO means LACK OF OBLIGATION (=don’t need to)

Together with OUGHT TO, they both express advice.

In the past, they both use HAD TO IES Diego Torrente Pérez

Eduardo Arcas Domínguez

How can we express ability? CAN It refers to a present general ability



It refers to a past ability

The verb to be lets us express ability in any tense.

Note the difference between them in the past It refers to a GENERAL past ability or PARTICULAR OCCASION when followed by see, hear, taste, feel, smell, understand, remember and guess IES Diego Torrente Pérez

Eduardo Arcas Domínguez


How can we express possibility? MUST

If you are totally sure




If there are some possiblities



IES Diego Torrente Pérez

If it is impossilbe

Eduardo Arcas Domínguez

How can we express other ideas? REQUESTS

CAN CAN--COULD COULD(polite) (polite)--MAY MAY(polite) (polite) -WOULD WOULD(formal) (formal)




CAN CAN––COULD COULD(polite) (polite)

IES Diego Torrente Pérez

Eduardo Arcas Domínguez

How else can we express a modality? BE TO Obligation [You are to stay here at 4] BE ALLOWED TO Permission [You are allowed to miss the lesson] BE BOUND TO Certain future deduction [He is bound to come] USED TO BE LIKELY TO Possibility [You are likely to pass the exam] Past habits [I used to be a good child] HAD BETTER OUGHT TO Advice [You’d better study more] WOULD RATHER Giving & asking for advice [You ought to study Preferences [I’d rather have a coffee ] more] DARE Nerve [I daren’t say the truth] NEED Obligation [Need I go?] NEEDN’T Lack of obligation [You needn’t come] Not NEED TO IES Diego Torrente Pérez Eduardo Arcas Domínguez Lack of obligation [You don’t need to come]

PERFECT MODALS MAV don’t usually have a PAST FORM. However, they are sometimes followed by the PERFECT INFINITIVE to talk about the past MUST MUST/ /MIGHT MIGHT/ / MAY MAY COULD COULD/ / COULDN’T COULDN’T SHOULD SHOULD/ / SHOULDN’T SHOULDN’T

IES Diego Torrente Pérez

It must be the milkman (Someone is knocking on the door) It must have been the milkman (The bottles are there but there is nobody at the door I could go out when I was 15 I could have gone out, but I didn’t want to You should go to the doctor (now) You should have gone to the doctor. Now it is too late.

Eduardo Arcas Domínguez

Modal Auxiliary Verbs  

Brief explanation of Modal Verbs

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