Hello, Mr. Bravo.
(1) Every verb has various forms:
eat = base
ate = past
eaten = past participle
eating = present participle
(2) use the past participle with any form of have:
I have eaten/ I had eaten/ She has eaten/ They will have eaten.
(3) use the present participle with any form of be:
I am eating/ You were eating/ He was eating/ They will be eating.
(4) If you use the passive, you use the past participle:
I eat an apple = An apple is eaten by me.
They ate apples. = Apples were eaten by them.
She will eat an apple. = An apple will be eaten by her.
If you have more questions, please post them.
Student or Learner