Modal verbs: Obligation, Prohibition and Advice

Presentation

Modal verb

Obligation

Modal verbs:

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Obligation

We use MUST and HAVE TO to express obligation

MUST

MUST shows us that the obligation comes from inside the speaker STRUCTURE: MUST + INFINITIVE

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HAVE TO

HAVE TO shows that the obligation comes from outside. This is usually refer to a rule or law. STRUCTURE: HAVE TO + INFINITIVE *Use do or does to make a question.

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LACK OF OBLIGATION

We use DON'T / DOESN'T HAVE TO or DON'T / DOESN'T NEED TO to show that there is no obligation. You can do something if you want but it is not an obligation. * It doesn't mean the same as MUSTN'T.

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EXERCISES

B. Choose the correct option: 1. You SHOULD / SHOULDN'T / HAVE TO eat too many calories, or you'll get fat! 2. She DON'T HAVE TO / DOESN'T HAVE TO / MUST tidy up now. I'll do it later 3. My brother HAVE TO / HAS TO / DOESN'T HAVE TO wear a tie at his work. He is a lawyer. 4. You MUSTN'T / MUST smoke in this office. It's a rule. 5. We MUSTN'T / DON'T HAVE TO forget to set the alarms before we leave

EXERCISES

C. Rewrite the sentences using the modal verbs given. 1. I think it would be a good idea for you to take a break. (should) 2. Students are allowed to buy cheap meals in the cafeteria. (can) 3. It's important that I remember to print out my essay. (must) D. Correct the underlined mistake. 1. Sally must go to bed early last night. 2. Students don't have to talk loudly in the library 3. Do we must hand in our homework today?

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tamar.tapia.vasquez@americancollege.cl