"My sister has a dog."

Translation: Mia sorella ha un cane.

[tango-alpha]

When do you say "mia sorella" vs. "la mia sorella"?

[barra86]

you never say "la mia sorella"

[cowcopter]

but so how do you know when a noun should have "la" or "il" before the possessive and when it shouldn't?