 Re: must and have to?????????
It's quite a complicated feature of English, and very confusing to foreigners.
"must" is a so-called modal auxiliary, and is also an example of a so-called defective verb. It is defective because there are some bits missing: it has no infinitive, no past participle and no present participle, for example. But sometimes you can't construct a sentence without one of these forms, and in this case English has an alternative: "have to". For example, you can't say: "I will must go", so you have to say "I will have to go".
There some idiomatic differences, as Coffa says, but apart from that, so far so good.
The problem is that the negative form of each version has a totally different meaning:
"You mustn't" means "You are not permitted" -- "You mustn't smoke here" means "Smoking is not allowed here."
"You don't have to" means "It is not necessary" -- "You don't have to go" means it's okay if you don't want to go.
In Britain, you mustn't walk down the streets with no clothes on. But you don't have to wear a hat if you don't want to.  |