Your friend borrowed your notebook for a moment and spilled water on it.
I saw a classmate cheating on an exam.
Your cousin gave you a sweater for your birthday, but I was not your size.
You found a dog with a collar on the street.
Your brother found a wallet on the street and kept it.
You are invited to a party you don't want to attend.
I would have told her that I didn't fit in it and return it.
I would have taken pictures of it and post it on social networks to find the owner.
I should have told the teacher about it.
I should have spoken to my friend about it.
He should have looked for the owner.
I would have told my friend I couldn't go.