MODAL VERBS EXPRESSING OBLIGATION
HAVE TO MUST
OBLIGATION IN THE PRESENT affirmative
Have to. Obligation comes from external rules. eg.You have to be 16 to leave school
Must. Obligation is imposed by the speaker or the speaker has authority over the person he/she is speaking to. eg.I must go now eg.You must be quiet during the exam
Make sentences using HAVE TO and MUST
Negative Don´t
have to Doesn´t have to
No Obligation
eg.You don´t have to finish the exercise e.g She doesn´t have to come at once
Prohibition
Mustn´t
Something is prohibited or it is important not to do it.
eg. You mustn´t eat in the clasroom eg. You mustn´t leave the school during school hours Eg. You mustn´t smoke anywhere in the school Eg. You mustn´t use mobile phones in the classroom
Use must or mustn´t to say something about these pictures
Compare these offices using don´t have to and mustn´t
Questions Do
you have to..? Does she have to..? Eg. Do you have to clean your room? Yes, I do Eg. Does he have to cook every day? No, he doesn´t
Do you have to ….?
Ask questions using Do you have to…?
OBLIGATION IN THE PAST
Affirmative Negative Questions
Had to Didn´t have to Did you have to
Eg. Yesterday I had to walk home because I missed the bus. Eg. She didn´t have to work on Saturday Eg. Did they have to tidy up the room before they left?