Rule reminder

Italian has several impersonal expressions of necessity/need: bisogna + inf (it is necessary), occorre + inf (formal, it is required), serve / servono + noun (it takes/one needs), ci vuole / ci vogliono + noun (it takes — time, effort, quantity). Bisogna and occorre are always singular. Serve/servono and ci vuole/ci vogliono agree with the noun that follows.