I'm currently going through the various "Hear It Say It!" phrases trying to change the verb tenses on the fly. I keep the verb conjugation web site on an adjacent tab as, more often than not, I need some assistance - particularly for some of the more lesser used tenses. One surprise for me is how different some of these past participles can be:
resolver (to resolve) - resuelto (resolved)
romper (to break) - roto (broken)
One phrase from the course uses "roto", and I would never have guessed that the root verb was romper: echar en saco roto - to do something in vain.