Modals

Must:

'must + infinitive' (for something that's likely about the present) or
'must + have + past participle' (for something that's likely about the past):

http://www.perfect-english-grammar.com/modal-verbs-of-probability-exercise-1.html

Must/Have to:

http://www.englishpage.com/modals/interactivemodal2.htm

All modals:

http://www.englishpage.com/modals/interactivemodal1.htm