Must/ have to (Unit 32,33)

We use must(do) and have to to say that it is necessaryto do something.

-|-	You must have a passport to visit most foreign countries. She has to wear glasses for reading.
<-|	I had to go to hospital.
|->	I must write to Ann. I haven't written to her for ages.

+	You must have a passport to visit most foreign countries. She has to wear glasses for reading.
?	Must you leave tomorrow? Why did you have to go to hospital?
-	You must not swim in that river. It's full of crocodiles. Tom doesn't have to work on Saturday.

With must the speaker is giving his own feelings, saying what he thinks is necessary.
With have to the speaker is just giving facts.
Mustn't - is necessary that you don't do it.
Don't have to or needn't - is not necessary to do it.

EXAMPLES:
I can hear you quite clearly. You needn't shout.