HAVE/HAS TO- DON'T/DOESN'T HAVE TO

 HAVE TO IMPLIES AN OBLIGATION

1.  https://agendaweb.org/exercises/verbs/modals/have-to

2. https://www.englisch-hilfen.de/en/exercises/tenses/have_to.htm

3. https://es.liveworksheets.com/yt33274sz 

4.  https://www.englishexercises.org/makeagame/viewgame.asp?id=12171

5.https://learnenglishkids.britishcouncil.org/grammar-practice/have-got

6. https://wordwall.net/es/resource/24470856/dont-have-to-doesnt-have-to/have-to-dont-have-to-has-to-doesnt 

7. https://www.elt-els.com/2015/02/modal-verbs-multiple-choice-test_15.html

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