10. The use of si
“Si” is a multipurpose word that is used in several different constructions.
It can be used in a passive sense, which means that the sentence does not have a subject. Passive si is formed by combining si with a verb in the third person singular or plural. The verb has an object:
In Italia si mangia molta pasta.
In Italy, a lot of pasta is eaten.
In Finlandia si parlano il finlandese e lo svedese.
In Finland, both Finnish and Swedish are spoken.
The verb is inflected according to the object. If the object (underlined) is singular or there is only one of them, the verb is inflected in third person singular. If the object is plural or there are multiple objects, the verb is inflected in third person plural.
A very similar construction is the impersonal si. It differs from the passive form in that the sentence does not contain an object. The verb is only inflected in the third person singular:
In Italia si mangia bene.
In Italy, one can eat well.
In Finlandia si parla poco.
In Finland, people speak little.
Finally, si can be found in reflexive verbs, which are verbs that usually refer to some form of self-directed action:
lavarsi ⇒ Susanna si lava.
Susanna washes herself.