Rule reminder

When 'si impersonale' is used with compound tenses, the auxiliary is always 'essere' and the past participle agrees in gender/number with the direct object (if present). In complex tense sequences, the si impersonale tense must reflect the correct temporal relationship to the main clause. With essere verbs: 'si è stati' (not 'si ha stati'). With avere verbs: 'si è mangiato', 'si è lavorato' (masculine singular agreement).