1.must was an order need comes from people who are talking or listening to 2.must
! When talking about what we're sure
3.Must. Can be used to tell the need for current events and future
4. Must means acting duty or regulations
5.Must is used with present tense only
6. When to use must in the form of sentences, it can fill the not in. In this case it means " Don't do anything by it
7. Mustn 't used to tell people not to do this.