Source:
https://scmp.com/article/490210/brush-your-grammar

Brush up your grammar

I have A toothache. The pain is terrible. The dentist will have to take the tooth out when the pain stops. He has given me some pills. I have to take them four times a day.

Bad news! Let's hope the toothache gets better quickly. The patient has to take painkillers. The dentist has to take the tooth out. When we say we have to do something, we mean that it is necessary to do it. We have no choice. It's an obligation.

I have to go to school.

We are going to be late. We have to hurry up.

William has to pass a lot of exams before he becomes a dentist.

All these actions are necessary. They have to do them.

A. Can you now complete these sentences? Use have to/has to and one of the verbs from the list.

1. Sunlight hurts my eyes in summer. I --------- dark glasses.

2. Kit starts work early. He -------- home at six every morning.

3. Alex's English is not very good. You -------- everything to him at least twice.

4. I'll see you in the morning. I -------- now.

5. Danny ------- his girlfriend at least five times a day.

6. My dad ------ to Australia tomorrow on business.

7. Harry is very lazy. He -------- harder next term.

8. They -------- house. The rent is too expensive for them.

repeat / wear / move / eat / travel / work / speak / leave / call / go

B. Negatives and the past

We use don't have to/doesn't have to when something is not necessary in the present. To speak about the past, we say had to and didn't have to.

I don't have to go to school next week. Great!

Denis doesn't have to go to work tomorrow morning.

I had to have a word with him about his punctuality.

She didn't have to wear a uniform when she was at school in Australia.

Here is a mixed bag of sentences. Can you put in the correct form of to have to?

1. I stay in bed until 10 on Saturdays. I ........... get up early.

2. Last week, I ........... buy a birthday present for my dad.

3. Andy .............. work last week. He had a week's holiday.

4. My mum ............. go into hospital last week for a serious operation.

5. Tonight, my dad ................ go visit my grandma in Tai Po.

6. In the UK, children ........... begin school at the age of five.

7. I ............. speak to you if I don't want!

8. Our teachers ............. get angry in class. We are all well-behaved.

9. The buses were on strike yesterday. I .............. walk to work.

10. Everyone ........... stand up when the principal comes into the room.

Answers

A. I have to wear/he has to leave/you have to repeat/I have to go/Danny has to call/my dad has to travel/he has to work/they have to move house

B. I don't have to get up early/I had to buy/Andy didn't have to work/my mum had to go/my dad has to go visit/children have to begin/I don't have to speak/our teachers don't have to get angry/I had to walk/everyone has to stand up