You mustn't/don't have to open the door for a stranger. A stranger may/should trick you. You have to/might answer the phone. You don't have to! may…

You mustn't/don't have to open the door for a stranger. A stranger may/should trick you. You have to/might answer the phone. You don't have to! may telleverybody that you are home alone . You must/might know your parents' phone number. It must/have to be wise to know your neighbours .