The past participle form of the verb is the form used with the helping verbs have, has, and had.
Jack has walked a mile today.
Jack and I have walked ten miles this week.
Before meeting Jack, I had walked by myself.
How long has he attended Tech?
The choir has sung every hymn in the book
The traveler had lost his way in the dark.
Error prevention: The past participle form of regular verbs are not the source of major errors. As with the simple past, the only thing that requires special attention is spelling: change the y to an i before adding the -ed to a present form that ends with y (study/studied, try/tried). If the simple present ends with an e, just add a d (live/lived).
The past participle forms of irregular verbs, however, are the source of many verb errors.
