1.  Verbi modali o servili  difettivi = mancano di alcune forme (infinitive, past participle, gerund)  Followed by dare infinitive  Same form for all persons ( no –s)  Use substitution forms fo infinitive and missing tenses e.g. can => to be able to must => to have to may => to be allowed to

2.  obligation/ order Students must be at school on time  intructions You must open the tin on this side  strong recommendation You must this this film: it’s amazing  deduction/speculation Where are my glasses? – They myst be in your bag

3.  Should If you don’t feel well, you should stay at home, you shouldn’t go to school  Ought to If she has asked for you help, you ought to help her, you oughtn’t to disappoint her.  Had better We had better hurry if we don’t want to miss the bus What a cold! You’d better take an aspirin!

4. Necessity/external authority/duty  She has to write an essay for tomorrrow  We have to keep our homes neat and tidy  We all have to be at school on time  I can’t make it today: I’ve got lots of things to do!

5. Must (rule: speaker’s authority)  Mum: “You must tidy up your room”  The law: ”Cyclists must wear a helmet” to have to (duty/necessity/external autority)  Son: “I have to tidy up my room”  Cyclist :”I have to wear a helmet” (external authority)  Cyclist “ I must wear a helmet” ( I feel it is important)

6. MUSTN’T prohibition  You mustn’t smoke at school  You can’t smoke…  Don’t smoke…  We weren’t allowed to ge into the gallery  We couldn’t get into the gallery DON’T/DOESN’T HAVE TO absence of necessity  We don’t have to wear a uniform  She doesn’t have to wash up: she has a dishwasher  We didn’t have to wait: the train earrived on time