cosa stai facendo ? whare are doing ? Actually /stai/ is stay, but probably you already know this. We don't say Cosa tu stai facendo for the simple reason that /stai/ implies /tu/ If you phone a friend or somebody you care for, you might uise this noce expression: Cosa fai di bello ? word by word is: what do of good ? This expression might for instance be in something like: -- Ciao Marco, che fai di bello ? Hai visto che bel sole oggi ? Cosa ne diresti di andare insieme da qualche parte ? ==== In the case you are an instructror, or you are suoervising somebody doing a difficult task (like cooking a complex cake), you could ask: a) cosa stai facendo adesso ? b) e adesso cosa fai ? The form (b) could also be used as a challenge, for instance if you just made a very clever move playing chess, you could use (b) with the right tome to imply that your adversary has now a difficult task to in front of him.

Like this: Cosa stai facendo? What are you doing

(Ma) Cosa / Che / Che cosa fai? Tu sei matto?!:)