A seated
with+名词或代词+过去分词,是独立主格结构,做伴随状语
seat做谓语时,是seat sb,sb be seated.但做状语,补足语,定语等时,就要去掉be,而保留过去分词seated.
I found my father seated on the chair.(做补足语)
The man seated on the chair was my father.（做定语）
Seated on the floor,they talked and laughed.(做状语)