Answer:
She wrote the prologue after she finished the entire book.
Step-by-step explanation:
An inappropriate shift in verb voice is basically when the voice of the verbs change in the sentence. Passive voice is when something experiences an action while active voice is when someone performs the action. In the original sentence, 'wrote' is active while 'has been finished' is passive, since the book is experiencing being finished.
While there are numerous approaches to edit a sentence, I reworded the sentence to make sure both voices are active as she is acting to do something.