Spanish/Tenses/Past participle

Some things to note:
 * 1) There are several irregular participles: romper (roto), volver (vuelto), resolver (resuelto), escribir (escrito), poner (puesto), decir (dicho), hacer (hecho), satisfacer (satisfecho), morir (muerto), cubrir (cubierto), ver (visto), abrir (abierto), imprimir (impreso but also the regular imprimido), freír (frito but also the regular freído).  -Er/-Ir double vowels, excluding -uir verbs, will place an accent over the 'i':  caer (caído), leer (leído), creer (creído), oír (oído), etc.  The participle of verbs composed of a prefix plus a previously mentioned irregular will follow the pattern:  devolver (devuelto), componer (compuesto), descubrir (descubierto), etc.
 * 2) The past participle can also be used as an adjective. If used as such, they must agree with the subject. Las palabras habladas (the spoken words), not las palabras hablado.
 * 3) The past participle is used with the verb ser to form the passive voice: Las casas fueron destruidas.  (The houses were destroyed.)
 * 4) Past participles are used in perfect tenses along with the verb haber.
 * 5) Past participles are non-finite, or impersonal, meaning they are not conjugated based on the subject of the sentence. Regardless of whether it is ellos, nosotras, or yo who have spoken, it is the verb haber that must agree with the subject, tense, and mood.
 * 6) "Las palabras habían sido habladas" (the words had been spoken) uses the past participle as part of the verb. Las palabras habladas uses it as an adjective.
 * 7) -ER and -IR verbs follow the same structure