'Accepted' is a past participle of 'accept' already.
accepted
Accepted
The past tense of "accept" is "accepted," and the past participle is also "accepted."
The past participle is equipped. Equipt is also accepted.
Accepted
The past tense of strike is struck, and the past participle is also struck.
accepted.
Present - accepting Past - accepted
The past tense of "sneak" is "sneaked" or "snuck," and the past participle is also "sneaked" or "snuck." Both forms are commonly used in English.
Most commonly stridden but strode and strid are also accepted.
The past participle of "am not" is "have not been."
The past participle of "do" is "done." The past participle of "have" is "had."
The past tense of "have" is "had," and the past participle is also "had."
The past and past participle for "buy" is "bought."