She went to the piano class after she finished school. Why "she finished school" but not "she was finished school"?

ill:-usually indirect , predicate usage.
eg:-He went to the doctor when he was ill with ( a disease.)
He was taken ill,(became ill) with a disease.
He was ill health ; in an ill condition.

she was finished school的文法除了錯之外，也變成是「她被"了結"了(被學校這死物殺了)」
文法句式由主體/主角/人物決定語法和意義的配合來表達，她上完學(放學)的主體動作是由她做出的，是她做完了(finish)一天的課堂(school)。
finish加ed是過去式記錄敘述她的事件。

Thanks how about

he was ill,

咁點上面 ill 又要用was?