To form the past participle in Spanish, you take the infinitive form of the verb and add -ado to verbs that end in -ar, and -ido to verbs that end in -er and -ir. ‘Amar’ becomes ‘amado’, ‘correr’ becomes ‘corrido’, ‘vivir’ becomes ‘vivido’. Past participles are used in various tenses or can act as adjectives, just like in English: ‘Una puerta cerrada’ = ‘A closed door’. As adjectives they have to agree with the noun they modify, so they can take the forms ‘-da’, ‘-dos’, -das’.