Prohibition in English is expressed by the modal verb must in the negative form (MUST NOT) which means that if something is prohibited or forbidden you aren’t allowed to do it. Obligation, is something that you are expected to do, and it is expressed by the modal verb must in the affirmative form (MUST). A necessity is something less stronger than an obligation and it is expressed in English by the verb HAVE TO.


 Information booth  Punto informazione
 Do you have a light?  Hai un accendino
 You’re not allowed to smoke indoors  Non è permesso fumare all’interno
 Outside in the parking lot  Fuori c’è un parcheggio
 No photos allowwed in this building  Non è permesso fotografare in questo edificio
 Why can’t I take a photo?  Perchè non posso fare una foto?
 Can I shoot some videos?  Posso fare qualche ripresa video?
 No videos allowed either  Neanche i video non sono permessi
 Anywhere outside the building is allowed  E’ permesso ovunque di fuori
 What if I want a picture of that?  E se volessi una foto di quello?
 You can buy a picture of that at the gift shop  Puoi comprare una foto di quello nel negozio di souvenir

Grammar Focus

Have to and must are followed by the infinitive without to. HAVE TO is used for more external obligation (things which are necessary). MUST is used more for personal obligations (things which I think are necessary, e.g. I must pass the test).

HAVE TO is used for general obligations (rules which apply to everybody, e.g. I have to get to work on time) and for external obligation.

MUST is used for personal obligations (moral or internal obligation). Also HAVE TO can be used for personal obligation when I don’t want to put too much emphasis on this obligation.

MUSTN’T (MUST NOT) is used for prohibition and negative obligation (e.g. You mustn’t smoke in here).

DON’T HAVE TO is used when you refer to something that is not necessary (e.g. I don’t have to work on Saturdays)

Obligation and necessity