169. The person by whom (or the thing by which) an act, indicated by a
passive verb or participle, is performed is called the "agent" of the
passive voice, and is expressed by a substantive preceded by "de":
La lanco estas portata de mi, the spear is carried by me.
La libroj estas jam presataj de li,
the books are already being printed by him.
La vojoj estas kovrataj de negxo,
the roads are being covered by snow.
Sxi estas lauxdata de la sinjoro,
she is being praised by the gentleman.