M UST Friday August 21st. M UST " Must" is most commonly used to express certainty. It can also be used to express necessity or strong recommendation, although native speakers prefer the more flexible form "have to." "Must not" can be used to prohibit actions, but this sounds very severe; speakers prefer to use softer modal verbs such as "should not" or "ought not" to dissuade rather than prohibit. E XAMPLES This must be the right address! certainty Students must pass an entrance examination to study at this school. necessity You must take some medicine for that cough. strong recommendation Jenny, you must not play in the street! prohibition Must is a modal verb. All modal verbs fallow the same rules: We only use one form for all persons. I must study. He must study. we must study. They must study. We do not add an s to must with he, she, or it. He must study. NOT he musts study. We always follow must with another verb in the base form. You must eat this pizza. NOT you must to eat this pizza You musnt go to school NOT you musnt to go to school We dont usedont / doesnt with the negative form of modal verbs You musnt talk Not you dont must talk. The negative form of must is must not. In spoken and informal written english, must not is usually abbreviated to musnt. You must not shout = You musnt shout We use must to talk about necessity. Necessity means that you cannot avoid doing something You must come home before 9:30 p.m. (Yu cannot come home after 9:30 p.m.) I must call Mel. Its her birthday today (you cannot call Mel tomorrow because it is her birthday today) We use Must to express general obligation. You musnt drive on the right in the U.S We use Musnt to express prohibition. You musnt use a dictionary in the test! You musnt use your cell phone in the class L ET S PRACTICE