Lesson 3: 'Mustn't' and 'don't have to'
In affirmative sentences, ‘must’ and ‘have (got) to’ really have the same meaning. But in the negative, their meanings are completely different.
Don’t have to / haven’t got to = you don’t need to / it’s not necessary
- You don’t have to get up early tomorrow. It’s a holiday! (Of course, if you want to get up early, that’s not a problem. You can choose.)
- We don’t have to eat breakfast at home. We can go to a café.
Mustn’t = it’s not okay to do something / it’s a bad idea to do something
- You mustn’t smoke so much! It’s really unhealthy.
- They mustn’t swim in that lake. It’s really dangerous!
- You mustn’t drive so fast!