Respuesta :
Avoir is to describe motion and direction and reflexive verbs use etre, you just have to memorize them as bad of an answer this is. With time you will come to understand which ones use it and which ones don't, it all comes down to memorization.
Etre verbs do not use avoir UNLESS it's in the passe compose.
You would use: Elle a fini le liver
Think of etre like to be, memorize these etre verbs: cliffsnotes.com/study-guides/french/french-i/french-i-the-passe-compose/the-passe-compose-with-etre
Etre verbs never use avoir unless it is etre itself.