PAST PARTICIPLE

Usual way to create a past participle:
Verbs that end in ~ar: replace ~ar with -ado (hablar/hablado)
Verbs that end in ~er: replace ~er with -ido (tener/tenido)
Verbs that end in ~ir: relace ~ir with -ido (construir/construido)
Common verbs that do not follow the above rules:
decir (to tell) - dicho
escribir (to write) - escrito
hacer (to make) - hecho
romper (to break) - roto
poner (to put) - puesto
ver (to see) - visto
volver (to return) - vuelto