"The winter has passed."
Translation:O inverno passou.
In this sentence, 'has' is a helping verb, expressing the past. You don't use the verb 'to have' as a helping verb in Portuguese. English uses a lot of helping verbs to express tense, while Portuguese prefers using inflection (different endings).
EDIT Oh yikes! reading this now I realize how wrong I was. Portuguese does indeed using helping verbs for the compound past. It's amazing how a reading of a grammar book has made everything much clearer.