Good evening dearest students and teachers alike!
The modal ''must'' and semi-modal ''have to'' can give anyone grey-hairs when we have to consider the idea...when we simply must understand it for more accurate speech...
Let's start off with why we use them :
(Must we go?/Do we have to?/I must go/We have to go.)
Sometimes, 'must' and 'have to' are interchangeable, but the guideline is that we use must for personal obligations (I must e-mail her right now.) and have to is used for responsibilities (I have to do a grading for each student after every lesson.)
In general, 'must' is used when the "obligation" is the opinion or idea of the person speaking. In fact, it is not a real obligation.We use it most regularly in ''everyday'' spoken English.
Examples:
I must cook dinner at five.
I must remember to call my friend.
I must take my vitamins.
I must finish sending e-mails before I go home.
Hang in there- do not fall asleep just yet!
'Have to' is often used to discuss our daily responsibilities and is commonly used to describe workplace situations. Many times, 'have to' is used in place of 'must' in informal English.
NOTE: 'have to' is conjugated/changed accordingly and therefore needs an auxiliary verb in the question form or negative.
Examples:
I have to start work at eight.
We don't have to wake up early.
They will have to arrive early. ( We often use semi-modals like ''have to'' with ''full modals'' --> will have to/ should have to/ might have to etc.)
Does she have to be so loud?
She has to arrive at work by seven a.m. ( She=third person= use ''has''.)
When we consider the negatives:
'Don't have to' and 'Mustn't' have very different meanings.
'Don't have to' is used to express that something is not a requirement.
'Mustn't' is used to express that something is prohibited.
Examples:
I am so lucky that I don't have to ride a scooter.
I mustn't ride my scooter without a license.
I must not throw chalk at my students.
You don't have to do the homework.
Negative form of 'have to' = 'Don't have to do' - Not a strict requirement- it is optional.You could do it if you wanted to!
Examples:
You don't have to eat breakfast. (your decision if you do.)
They didn't have to get here early.
We don't have to stay at the party until late. ( We can leave early.)
She didn't have to attend the lesson.
Must not do- contracted in natural speaking to, ''Mustn't do'' - Of course-is stronger than Do not have to- contracted in natural speech to, ''don't have to.''
Mustn't do signals Prohibition- something you are not allowed to do!
Examples:
She mustn't shout at them!
You mustn't treat her so badly.
You mustn't drive that scooter without a license
Nota Bene :
The past form of 'have to' and 'must' is 'had to'.
'Must' we do not use in the past. (We can not say ''musted.'')
Examples:
Did he have to leave?
He had to work over-time.
She had to pick her son up from school at five.
Do you have to be so irrational?
