In compound tenses with the auxiliary avere, the past participle usually ends in -o—unless preceded by a direct object pronoun (lo, la, li, le), which requires agreement.
When the relative pronoun che (that/which) acts as the direct object, making the past participle agree with the noun it replaces is optional.
While you can safely leave the ending as -o, making it agree is considered elegant and is common in written Italian. Notice how the past participles below match the gender and number of the preceding nouns (le cianfrusaglie, i libri):
| The knick-knacks that I have accumulated are too many. | Le cianfrusaglie che ho accumulate sono troppe. |
| I must tidy up the books that I have accumulated over the years. | Devo riordinare i libri che ho accumulati negli anni. |
Decluttering Your Space
When it is time to tidy up (riordinare), you often deal with boxes or piles (il mucchio) of things that clutter (ingombrare) the room. During the sorting process (la cernita), you decide what to keep and what is completely unusable (inservibile) and ready to be discarded (scartare).
| During the sorting, I saw the photos that you discarded. | Durante la cernita, ho visto le foto che hai scartate. |
| The boxes that you have accumulated clutter the room. | Le scatole che hai accumulate ingombrano la stanza. |
It is easy to throw away broken things, but it is often much harder to get rid of (sbarazzarsi di) objects that carry emotional (affettivo) weight.
| I know that it is difficult to get rid of objects with an emotional value. | So che è difficile sbarazzarsi degli oggetti con un valore affettivo. |
| The frames that I have discarded have an emotional value. | Le cornici che ho scartate hanno un valore affettivo. |