MUST Vs HAVE TO

We  use ‘must’ to express a strong obligation. When we use ‘must’ this usually means that some personal circumstance makes the obligation necessary (and the speaker almost certainly agrees with the obligation.)

• I must get up earlier.
• She  must do something about it.

We  use ‘have to’ to express a strong obligation. When we use ‘have to’ this usually means that some external circumstance makes the obligation necessary.

• I have to arrive at work at 8 o’clock. My boss is very strict.
• You have to pass your exams or the university will not accept you.

NOW, TRY THE EXERCISES: 

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

https://www.englishclub.com/grammar/verbs-modals-have-to-must-not-quiz.htm

http://www.learn-english-today.com/lessons/lesson_contents/exercises/must-haveto_quiz1.htm

http://www.agendaweb.org/verbs/modals-must-have-to-exercises.html