The English equivalents of the passato prossimo, using the verb mangiare in the first person singular are as follows: I have eaten, I ate, and I did eat (emphatic).
The passato prossimo is a compound tense, formed with the appropriate form of an auxiliary verb (avere or essere) and the past participle of the verb. The past participle of regular verbs is formed by adding an appropriate ending to the infinitive stem. See the following table for each of the three verb conjugations, in which the stem of each verb is in bold.