The modal verb “must

Must  is one of the modal verbs we use most in English. But how and when do we do it? Keep reading and find out!

When is it used?

We use must to indicate duty or obligation to do something; We could translate it as having or  duty . Beware, because in its negative form, it mustn’t indicate prohibition. To talk about something that  you have to do , but you could do, use  not + have to : You Do not Have to Eat That if you do not want to ( do not have to eat it if you want ), but You mustn ‘ t smoke in here! ( You shouldn’t smoke here! Don’t smoke here! )

How is it used?

Affirmative

Note: it does not change for the third person singular:  She must go now .

Negative

Interrogative

For the interrogation we hardly use must , we almost always resort to have to .