Unit 2
Gammar Contents:
We often use have to to say that something is obligatory, for example:
Children have to go to school.
Use of have to
In general, have to expresses impersonal obligation. The subject of have to is obliged or forced to act by a separate, external power (for example, the Law or school rules).Have to is objective. Look at these examples:
- In France, you have to drive on the right.
 - In England, most schoolchildren have to wear a uniform.
 - John has to wear a tie at work.
 
In each of the above cases, the obligation is not the subject's opinion or idea. The obligation comes from outside.
| subject | auxiliary verb | main verb have  | 
					to-infinitive | ||
|---|---|---|---|---|---|
| + | She | has | to work. | ||
| - | I | do not | have | to see | the doctor. | 
| ? | Did | you | have | to go | to school? | 
Mustn't do something = it's prohibited to do it.
Don't have to do something = you don't need to do it but if you want, you can.