Modali: can, must, should, have to, may

Caratteristiche dei modali

Regole generali

• Non si coniugano con -s alla 3ª persona singolare (he can, NOT he cans);
• Seguiti dall'infinito senza "to" (he can swim, NOT he can to swim);
• Forma negativa: modal + not (cannot, must not, ecc.);
• Forma interrogativa: modal + soggetto + verb (Can you swim?);
• No ausiliari: domande/negazioni senza "do/does/did".

Can

Significati

1. Capacità (essere in grado)

• I can swim. (so nuotare)
• He can speak Italian. (sa parlare italiano)
• She can't drive yet. (non sa ancora guidare)

2. Permesso (informale)

• Can I leave now? (Posso andare ora?)
• You can go. (Puoi andare.)
• You can't smoke here. (Non puoi fumare qui.)

3. Possibilità (generale)

• It can rain in summer. (Può piovere d'estate.)
• This medicine can cause side effects.

Forme

• Affermativa: can
• Negativa: cannot / can't
• Interrogativa: Can + subject + verb?
• Passato: could (could swim, could not / couldn't)

Must

Significati

1. Obbligo forte (regole, leggi)

• You must wear a seatbelt.
• Drivers must stop at red lights.
• Citizens must follow the law.

2. Deduzione logica (forte)

• He must be tired (è quasi certo che sia stanco).
• She must be Italian (presumibilmente è italiana).

Forme

• Affermativa: must
• Negativa: must not / mustn't (PROIBIZIONE — non DEVI)
• Interrogativa: Must + subject + verb? (raro, sostituito da "Do I have to?")
• No passato/futuro: si sostituisce con "had to" o "will have to".

Attenzione: must not vs don't have to

• Must not (mustn't) = proibito: You mustn't smoke = è proibito;
• Don't have to = non necessario: You don't have to come = non sei obbligato (puoi se vuoi).

Have to

Significato

• Obbligo esterno (regole, situazioni);
• Simile a must ma più "neutro";
• Più comune del must in inglese parlato.

Forme

• Affermativa: I have to / he has to (3ª persona +s);
• Negativa: don't have to / doesn't have to (= non sei obbligato);
• Interrogativa: Do/Does + subject + have to + verb?
• Passato: had to;
• Futuro: will have to.

Esempi

• I have to work tomorrow.
• She has to pay the fine.
• Do you have to leave now?
• Yesterday I had to drive 200 km.

Differenza must vs have to

• Must: obbligo personale o regole importanti;
• Have to: obbligo esterno generico;
• Negative:
  • mustn't = proibito (non è permesso);
  • don't have to = non obbligatorio.

Should

Significati

1. Consiglio

• You should rest.
• You should see a doctor.
• They should be more careful.

2. Aspettativa logica

• The train should arrive at 5 PM.

Forme

• Affermativa: should
• Negativa: should not / shouldn't
• Interrogativa: Should + subject + verb?
• Sinonimo: ought to (più formale).

Esempi

• You should pay the fine within 5 days.
• They shouldn't drive so fast.
• Should I call the police?

May / Might

Significati

1. Permesso (formale)

• May I come in? (formale)
• May I help you?
• You may leave now.

2. Possibilità

• It may rain tomorrow (probabilità);
• He might be at home (probabilità più bassa).

Forme

• Affermativa: may / might
• Negativa: may not / might not
• Interrogativa: May + subject + verb?

Differenza may/might

• May: probabilità più alta;
• Might: probabilità più bassa;
• Permesso: solo "may", non "might".

Confronto modali

Esempi per la Polizia Locale

Can (informale)

• Can I see your driving licence?
• Can you tell me where you are coming from?
• You can wait in your car.

May (formale)

• May I help you?
• May I see your documents?
• May I take notes?

Must (regole, obblighi)

• You must show your identity card.
• Drivers must stop at the police.
• You must sign here.

Have to (procedure)

• You have to pay the fine within 60 days.
• I have to write a report.
• We have to check the documents.

Should (consigli)

• You should wear a helmet.
• You should be more careful.
• You should pay quickly.

Cannot / Must not (divieti)

• You cannot park here.
• You must not drive without a licence.

Errori comuni

1. Aggiungere -s alla 3ª persona

• ❌ He cans speak → ✅ He can speak
• ❌ She musts go → ✅ She must go

2. Aggiungere "to" dopo modali

• ❌ I can to swim → ✅ I can swim
• ❌ You should to rest → ✅ You should rest

3. Confondere must / have to

• ❌ I must to work → ✅ I have to work / I must work

4. Mustn't vs don't have to

• ❌ You mustn't come if you don't want → ✅ You don't have to come
• ❌ You don't have to smoke (= proibito) → ✅ You mustn't smoke

Quiz mentale

Choose the correct modal:

1. _____ I open the window? (formal request) → May
2. You _____ wear a seatbelt (rule). → must
3. You _____ rest (advice). → should
4. I _____ swim very well (ability). → can
5. You _____ pay 50 euros (obligation). → have to

Per il concorso

Domanda tipica

"How do you use the main modal verbs in English?"

Risposta:

• Can: capacità (I can swim), permesso informale (Can I go?), possibilità (It can rain);
• Must: obbligo forte/regole (You must stop), deduzione logica (He must be tired);
• Have to: obbligo esterno (I have to work) — meno forte di must;
• Should: consiglio (You should rest), aspettativa logica;
• May: permesso formale (May I help?), possibilità (It may rain);
• Might: possibilità più debole;
• Forma: modal + verb (no -s, no to);
• Negazione: must not = proibito, don't have to = non obbligatorio.