2 תשובות
למשל:
i have read this book active
this book have been read by me. passive

they have done it bedore active
it has been done by them before passive

בעיקרון הנוסחה:

have\has + been + v3
אם כבר אז this book has been read. אבל השאלה היא לגבי past perfect ולכן בניית המשפט היא: before you read this book it had been read by me.