HomeGrammarModals of ObligationModals of Obligation admin 5 August 2015 Grammar No Comments Modals of Obligation;Must; official, written rules, strong recommendationHave to; when it’s necessary to do sth(no choice), very strong recommendationShould; soft recommendation or personal advice Tweet Pin It Related Posts Use Of In, On, At Prepositions Conditional Sentences Uses of ‘So’ and ‘Too’About The Author admin