Modals of obligation: Have to / Don't have to

We often want to talk about choices. For example,

1. "What do you want: a chicken sandwich or a cheese sandwich?" Here there is a choice. You can eat chicken or cheese. "You don't have to eat chicken. You can eat cheese."

2. "What do you want: a chicken sandwich or a chicken sandwich?" Here there is no choice. You can only eat chicken. "You have to eat chicken."

 

We use have to when we have no choice. We use don't have to when we have a choice.

 

Remember: 4 words       have to no choice                     don't have to choice

 

When we use he/she/it we need to change the words. With he/she/it, we use:  

                                                                                          has to   and  doesn't have to

 

We use have to to make questions. We change the word order when we make questions:

 

do I have to? do you have to? does he have to? do we have to? do they have to?

 

The past of have to is had to. The past of don't have to is didn't have to. With questions, we say:

 

did I have to? did you have to? did he have to? did we have to? did they have to?

 

Try these exercises: 

 

http://www.englishexercises.org/makeagame/viewgame.asp?id=8969