This document discusses the proper uses of must, mustn't, have to, and don't have to in the English language. Must is used to express obligation, especially from a position of authority. It is only used in the present tense. Have to is used to talk about obligations from rules, laws, or other people. Mustn't expresses something that is prohibited or against the rules. Don't have to means that an action is not obligatory. The document provides examples for how to properly use each term.

1. OBLIGATION and PROHIBITION

2. Weusemustwhen we think it is important to do an action or we give people orders, especially when you are in a position of authority. “You must be home by ten.” “She must tidy her room before she goes out.” MUST

3. Mustis only used in the present. We use forms of have tofor all other tenses. “We’ve missed the bus, so we’ll have towalk home.” “We had to study Philosophy at school.”

4. Weoften use must when the sense of obligation comes from the speaker. “I mustgo to the doctor.” (I don’t feel well)

5. Weoften have totalk about an action that is necessary because of rules or, or because someone obliges us to do it. “You have to drive on the left in the UK.” HAVE TO

6. “Do I have to buy a grammar book? “At school my children have towear a uniform.” “I have topay the rent every month.” “In Spain you have to go to school until you’re sixteen years old.” HAVE TO

7. We use mustn’tto say that something is against the rules, or against the law. “You mustn’tsmoke at school.” “I mustn’t be late for the meeting.” “You mustn’tuse a computer on a plane.” MUSTN’T

8. We use don’t have to to say that people are not obliged to do something. “You don’t have to get up early at the weekend.” “We don’t have tohurry; we are early.” “You don’t have toshout. I can hear you.” DON’T HAVE TO

9. * MUST and MUSTN’T are the same for all persons. * MUST is not often used in questions. (HAVE TO) is more common. * Don’t contract HAVE or HAS. I have to go. NOT I’ve to go