B1 · Can, must, want
Mustn't and needn't
« Mustn't » and « needn't » — you make this distinction already.
At a glance
- Remember
- non dovere mostly forbids; a clear « need not » wants obbligato or bisogno.
- Form
- (io) non devoI must not
- Signal words
- non devi
- obbligato a
- bisogno di
- non occorre
- Trap
- Wrong:Non sei obbligato venire, se sei stanco.Right:Non sei obbligato a venire, se sei stanco.
Your turn
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The form
How the forms are built
Each row gives the meaning first, then the form in Italian. The colours show what changes from one form to the next.
stem (regular) stem (irregular) person ending negation
| I must not | (io) non devo |
| you must not | (tu) non devi |
| he / she must not, you must not (formal) | (lui / lei / Lei) non deve |
| we must not | (noi) non dobbiamo |
| you must not (plural) | (voi) non dovete |
| they must not | (loro) non devono |
| you do not have to | non sei obbligato a |
| one must not | non bisogna |
| it is not necessary | non occorre |
| there is no need to | non c’è bisogno di |
| I cannot, I may not | (io) non posso |
| you cannot, you may not | (tu) non puoi |
| he / she cannot, you cannot (formal) | (lui / lei / Lei) non può |
| we cannot | (noi) non possiamo |
| you cannot (plural) | (voi) non potete |
| they cannot | (loro) non possono |
The rules one by one
The form this topic is about
non dovere sounds like a prohibition; the absence of a duty only with something added, such as per forza.
Non devi aprire quella porta.You must not open that door.
For « you do not have to » use non essere obbligato a or non c'e bisogno di.
Non sei obbligato a venire.You do not have to come.
non bisogna forbids as well.
Non bisogna dirlo a Paolo.One must not tell Paolo.
obbligato takes a, bisogno takes di, dovere takes nothing.
Non c’è bisogno di partire presto.There is no need to leave early.
Example sentences
Non devi fumare qui.You must not smoke here.
Non sei obbligato a rispondere subito.You do not have to answer straight away.
Non bisogna lasciare la chiave fuori.One must not leave the key outside.
Non occorre richiamare.There is no need to call back.
The trap English speakers fall into
Watch out
English already draws this line, which makes the mistake easier rather than harder: « you don't have to come » feels like an ordinary negative, so it comes out as non devi venire, and without context that is heard as « you must not come »; only per forza makes it clear. The safe form is non sei obbligato a — and it carries the second mistake: the a cannot be dropped, any more than the « to » in « obliged to come ».
The full explanation
Read it all · about 1 min
One word separates two worlds: « you must not » forbids, « you do not have to » excuses. Italian separates them with two different constructions rather than two words.
Forbidden is usually non devi; « need not » is read into it only from the context or with something added — domani non devo lavorare, non devi per forza venire. Clearly not necessary is non sei obbligato a or non c'è bisogno di.
The same holds for bisogna: non bisogna is a prohibition, hardly ever the absence of a duty. For the second, say non è necessario or non occorre.
Non puoi covers both « you cannot » and « you may not ». The context carries the difference, exactly as English « can't » does.
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The verbs on this page, in every form: essere · dovere · venire · lasciare · aprire · partire · rispondere · richiamare