lunes, 13 de marzo de 2017

Modal verbs

The modal verbs include can, must, may, might, will, would, should. They are used with other verbs to express ability, obligation, possibility, and so on. Below is a list showing the most useful modals and their most common meanings:

canto express abilitycan speak a little Russian.
canto request permissionCan I open the window?
mayto express possibilitymay be home late.
mayto request permissionMay I sit down, please?
mustto express obligationmust go now.
mustto express strong beliefShe must be over 90 years old.
shouldto give adviceYou should stop smoking.
wouldto request or offerWould you like a cup of tea?
wouldin if-sentencesIf I were you, I would say sorry.

Modal verbs are unlike other verbs. They do not change their form (spelling) and they have no infinitive or participle (past/present). 
The modals must and can need substitute verbs to express obligation or ability in the different tenses. Here are some examples:

Past simpleSorry I'm late. I had to finish my math test.
Present perfectShe's had to return to Korea at short notice.
FutureYou'll have to work hard if you want to pass the exams.
InfinitiveI don't want to have to go.
Past simpleI couldn't/wasn't able to walk until I was 3 years old.
Present perfectI haven't been able to solve this problem. Can you help?
FutureI'm not sure if I will be able to come to your party.
InfinitiveI would love to be able to play the piano.

Modals are auxiliary verbs. They do not need an additional auxiliary in negatives or questions. For example: Must I come? (Do I must come?), or: He shouldn't smoke (He doesn't should smoke).

A quiz on modals: