The analytical passive voice
In Spanish, the passive voice is used to emphasize the recipient of an action rather than the person or thing that performed it. This structure is often used in formal writing, historical accounts, and news reports.
To form the analytical passive voice, use a conjugated form of the verb ser (to be) followed by a past participle.
If you want to mention who or what performed the action (the agent), use the preposition por (by) followed by the agent.
Gender and number agreement
The most important rule in the analytical passive voice is that the past participle must agree in gender and number with the subject (the recipient of the action).
| The castle was conquered by a famous emperor. | El castillo fue conquistado por un famoso emperador. |
| The new structure was built by the masons. | La nueva estructura fue construida por los albañiles. |
Notice how conquistado ends in -o to match the masculine singular castillo, while construida ends in -a to match the feminine singular estructura. This applies to plural subjects as well.
| The bells were installed by the workers. | Las campanas fueron instaladas por los obreros. |
| The stained glass windows were designed by those who built the cathedral. | Los vitrales fueron diseñados por quienes construyeron la catedral. |
Passive voice with pronouns
The subject of a passive sentence can also be a pronoun, even if it is omitted (such as "we" or "I"). The verb ser and the past participle will adjust to match who is receiving the action.
| We were helped by the mason, from whom we learned a lot. | Fuimos ayudados por el albañil, de quien aprendimos mucho. |