1. Modal verbs
Meanings and use

2. Main modal verbs
Must
Have to
Ought to
Need to
Should
Can/ could
May/might

3. Main values / meanings
Must – obligation imposed by the speaker
Have to – obligation imposed by a situation (external obligation)

4. MUST & HAVE TO I must finish my homework before 8
We have to start work at 9 am
They are both used to express that something is necessary

5. MUST
I must find a hotel to stay at tonight (“I have to find a hotel” is also possible)
The speaker decides that something is necessary (INTERNAL decision)

6. HAVE TO I have to wear a uniform
Somebody else has made the decision, it’s not the speaker’s opinion (EXTERNAL decision)

7. MUSTN’T & DON’T HAVE TO Very different meanings in negative:
You mustn’t open the door
You don’t have to open the door

8. Affirmative / negative differences
Have to (obligation) /vs/ don’t have to (lack of obligation)
Must (obligation) /vs/ mustn’t (prohibition)

9. MUSTN’T & DON’T HAVE TO Very different meanings in negative:
You mustn’t open the door
You don’t have to open the door

10. MUSTN’T
You mustn’t open the door. Lately there have been many robberies in the neighbourhood.
(It’s forbidden /prohibited)

11. DON’T HAVE TO You don’t have to open the door. I have the keys.
(It’s not necessary)

12. Student worksheet 1
Modals and Related Expressions must have to 1. I ……….be at the meeting by 10:00. I will probably ………..take a taxi if I want to be on time. 2. You ………..submit the application if it has not been completely filled out. Check that the name, address, and background information are correct. 3. A: Look at these flowers - they're beautiful! But, there's no card. Who could have sent them? B: It ………have been David. He's the only one who would send you flowers.

13. 4. You ………. forget to pay the rent tomorrow
4. You ……….forget to pay the rent tomorrow. The landlord is very strict about paying on time.
5. You ………….. be so rude! Why don't you try saying "please" once in a while.
6. If you are over 18 in California, you ……. take a driver training course to get a driver's license.
7. You …………be rich to be a success. Some of the most successful people I know haven't got a penny to their name.