Relier Pairs Must have toVersion en ligne The correct use of must , have to and their negative form par Sabs Negrete 1 You have no choice. 2 Forbidden or not allowed to do 3 Formal or written obligations 4 It isn't necessary, just and advice 5 Not necessary and you can choose 6 A personal very important, necessary thing to do 7 It is an obligation from the situation. SHOULD & SHOULDN'T HAVE TO MUST DON'T HAVE TO MUST HAVE TO MUST NOT