2. Must – have to – to be to.

We use “must” to say that it is necessary to do something (express obligation).

E.g.The floor is dirty. You must sweep it.

Both must (do) and have to (do) express a strong obligation.

There is a difference between them. With must the speaker expresses his own opinion.

E.g.I must stop eating cakes. (I want to).

“Have to” expresses a general obligation based on a law or rule.

E.g.I have to stop drinking. (Doctors order me to)

Generally, “have to” is used more often than “must”. If you are unsure which to use, it’s safer to use “have to”.

Unlike must (present) “have to” can be used in all forms.

E.g.I had to talk to her yesterday.

E.g.Have you ever had to stay at work for 16 hours?

Note that we use do/ does/ did with “have to” in present and past questions and negative sentences.

E.g.John doesn’t have to do his homework.

E.g.Do you have to pay extra money for this service?

E.g.They didn’t have to spend too much time there.

E.g.Did she have to look after her aged uncle?

The negatives “mustn’t” and “don’t have to” are completely different.

“Mustn’t” expresses negative obligation– it’s important not to do smth.

E.g.You mustn’t offend children. It is disgusting.

E.g.You mustn’t play with the gun. It’s dangerous.

‘Don’t have to’ expresses the absence of obligation – you don’t need to do something (you can if you want but it isn’t necessary).

E.g.You don’t have to stay here till 10, you can leave earlier.

Be to is used in formal instructions.

E.g.No one is to enter this room (No one must enter this room).

You are not to leave this room.

Also we use this structure to talk about official plans and fixed personal arrangements.

E.g. The delegation is to arrive in September.

The clerk said the plane was to arrive two hours later.

Are you to write this article on Friday?

Ex. 5. Put in must or have to.

1. This is a great film. I … see it.

2. My hair is dirty. I … wash it.

3. You hair is dirty. You … wash it.

4. You’re ill. You … to stay in bed.

5. I am feeling so bad. I … stay in bed.

6. I have a headache. I … go and see the doctor.

7. I … to go to work by 9 o’clock.

8. I … to go to Paris for a meeting.

Ex. 6. Put in must or had to.

1. She … leave home at 6 every morning last year.

2. When his eyesight was bad he … wear glasses all the time.

3. When our typist was on holiday I … do all the typing at my office.

4. The window are so dirty. I … clean them.

5. We … hurry, or we might be late.

6. I never remember his address, I always … look it up.

7. It was raining and we … wait for a taxi for half an hour!

8. As I was late for the bus I … take a taxi.

Ex. 7. Make questions with have to. Some are present and some are past.

1. “She has to leave early”. What time does she have to leave?”

2. “She felt ill and had to leave early”. Why ………………?”

3. “He has to cook his own meals. His wife is away. Why ……….?”

4. “I have to get up early tomorrow.” What time ……………….?”

5. “We had to pay a lot of money for the license. How much ………?”

6. “Ben has to work tonight. Why ……………….?”

7. “He has to stay alone till his mother returns. How long …………?”

8. “We have to carry everything home ourselves! How many things exactly …..?”

9. “I had to ask a policeman the way. Why ………………?”

10. “She has to answer a lot of questions every day. How many questions ……….?”