The document discusses the use of "have to" and "don't/doesn't have to" to express necessity or obligation. "Have to" is used to say that something is necessary or important to do, like "I have to go now" or "You have to be careful." "Don't/doesn't have to" is used to say that something is not necessary or obligatory, like "You don't have to pay for it." Questions are formed with "do/does" and the past form is "had to/didn't have to."

1. HAVE TO / DON’T HAVE TO BY M. LUISA GUZMÁN

2. We use “have to” to say that it is necessary or very important to do something. I’m late. I have to go now. You have to be careful when you ride your bike in traffic. We have to be at school at 8:30. Their computer is broken, so they have to get a new one.

3. With a third person singular subject (he, she, it) we use “has to”. Jimmy is very ill – He has to stay in bed. My mother has to go to London tomorrow for a meeting. If she wants to be successful she has to be determined. If she wants to be successful she has to have a dream.

4. We use the negative form: “ don’t /doesn’t have to” to say that it isn’t necessary or important to do something. It is early, so you don’t have to hurry. The ticket is free – You don’t have to pay for it. My brother has got a motorbike, so he doesn’t have to walk to work. Diana doesn’t have to get up early on Sundays.

5. Questions are formed with “ do or does”. Do I have to go to school? Does he have to pay? Do we have to leave now? 4) The past form is “had to/didn’t have to”. Joanna had to go to the dentist last week. Yesterday was a holiday, so we didn’t have to go to school. Did you have to do the ironing last night? 5) All forms of “have to” are followed by the base form of the verb.