This worksheet lets students practise the form and function of the modal verbs of necessity (have to, don’t have to, must, mustn’t). It focuses on letting the learner choose the right verb to complete the sentences. It also explores the idea of choice when it comes to rules to help students understand the concept of modal verbs (you have a choice in life, but if you don’t do what “you have to/must do”, there will be a punishment/negative consequence. “Don’t have to” there is a choice.) There is an answer key.