We don’t use to after modal verbs.
Example She can’t to speak Japanese. He should to study more.
Have and has are followed by to.
Example I have to finish my email before I go home.
Do you have to work at the weekend?
We add not or n’t (not don’t or doesn’t) to make a modal verb negative.
Example You shouldn’t phone him until after 9 a.m.
He can’t drive.
To make questions with modal verb, we put the modal before the subject.
Example Can I park here? Where can I park?
We usually use have to instead of must for questions.
Example Do I have to take my passport?
Use
We use modal and related verb to talk about how to do the right thing or behave correctly in social and work situations.
We can also use the imperative to give advice.
Example Don’t forget to take your passport.
Introduce yourself to your new colleagues.
We use a polite tone of voice so that these forms do not sound too direct.