Direct object pronouns with the passato prossimo

You have learned that when you use avere in the passato prossimo, as in ho visto un bel film or abbiamo finito di fare la spesa, visto and finito do not change, no matter who is performing the action.  There is one exception to this rule: when the direct object pronouns lo, la, li, le and ne precede the passato prossimo, the past participle (visto and finito in our examples) changes to agree with the direct object pronoun. Study all the following cases:

With the direct object pronouns mi, ti, ci and vi, you do not have to do this agreement, but you may.