Modal verbs are used to express obligation, permission, possibility, and other attitudes. Some common modal verbs include must, should, can, may, might, will, would, shall, and ought to. Modal verbs have certain grammatical features - they are invariable, do not require do-support in questions and negatives, and are followed by the bare infinitive form of other verbs. Other verbs like have to, be able to, and need to share some uses and meanings with modal verbs as well.

1. Look at the sentences Marge says

2. You must go out = OBLIGATION You should go out = ADVICE You can go out = PERMISSION

3. must, should, can... are called MODAL VERBS OR MODAL AUXILIARY VERBS

4. Modal verbs are used to express the subjective attitudes and opinions of the speaker including possibility, probability, necessity, obligation, permission, ability, and desire.

5. What are modals can could may might must shall should will would ought to

6. Some features of the modals

7. -Modal verbs are invariable: one form for all the persons. That means you mustn't add -s to the third singular person. She musts study. OR She must studies

8. -Modal verbs don't need the "do support" in negative and interrogative sentences. You don't should tell him. You shouldn't tell him. Do you can swim? Can you swim?

9. -Modal verbs are always followed by the base form of the verb (infinitive without TO) You must to go. You shouldn't eating so much.

10. -Modal verbs do not have either the infinitive form, the past participle, the future tense, or the -ing form

11. WARNING All these rules must be applied to modal verbs. But what about the verbs HAVE TO BE ABLE TO and NEED TO ?

12. HAVE TO and BE ABLE TO do not share all the features of the modals but they do share some of the uses: obligation= ability= HAVE TO BE ABLE TO

13. Let's see some examples... I don't have to wake up early tomorrow. It's Sunday. You will have to study hard if you want to pass the exam. She has to go now. Her mum is waiting for her. Do you have to work at the weekend?

14. NEED TO is not a modal verb since it has the same forms as the so-called full verbs (go, change, drive, drink,etc.)

18. POLITE REQUEST COULD - Could you help me with this exercise? It’s so difficult. COULD is also used to make a polite suggestion. A: I’m going to Holland next week. B: Oh, really? You could visit your Dutch relatives then. MAY - Mrs. Lola, may I go to the toilet?

19. REQUEST & co. WILL YOU? (ask someone to help you) - Will you help me with the suitcases, please? They’re so heavy. WOULD (formal request) - Would you open the window, please? It’s so hot in here. SHALL I? (offer to help someone) - Shall I help you with your luggage? WOULD (make an offer) - Would you like a sandwich?

21. NECESSITY/OBLIGATION MUST HAVE TO The obligation comes from the speaker The obligation doesn’t come from the speaker MUM: You must be home by 11 o’clock. You go out. When it’s time to go, you can say: “ I’ll leave. I have to stay home by 11 o’clock.”

25. MUST certainty that something is true - It’s 8 o’clock. Sally must be at work. (I’M SURE) CAN'T certainty that something is impossible - It’s 8 o’clock. Sally can’t be at home. (IT’S IMPOSSIBLE)

27. POSSIBILITY CAN Scissors can be dangerous if not used properly. (+++possible) MAY (++possible) I may go to the party. (I’m not sure, it’s possible) MIGHT (+possible) I might go to the party. (I’m not sure, it’s improbable)