Have to
Must, Must not/Mustn't

Must is a modal auxiliary verb.

Have to is NOT an auxiliary verb (it uses the verb have as a main verb). We include have to here for convenience.

In this lesson we look at these two verbs, followed by a quiz to check your understanding:

• Have to (objective obligation)
• Must (subjective obligation)
• Must not/Mustn't (prohibition)
• Have to, Must, Must not Quiz