We use Must or Have to, to say that it is necessary to do something. Often it doesn’t grammatically matter which you use. However, in some situations they mean different things. Must is used when we are giving our personal feelings and Have To is used for impersonal things, for example a rule or a situation. Examples:
- I must get up early tomorrow. (There are a lot of things I want to do) PERSONAL
- I have to get up early tomorrow. (I’m going on holiday and my flight leaves very early) IMPERSONAL SITUATION
- I must wear a suit. I want to look good. PERSONAL
- I have to wear a suit. It’s the company’s policy. IMPERSONAL RULE
Negative:
- You mustn’t park here. It is against the law.
- You don’t have to park here. You can if you want to, but you could park somewhere else.
Practice this grammar by clicking here.