①表时间,相当于一个时间状语从句,有时过去分词前可加连词when或while来强调时间概念。 Seen from the top of the hill, the city looked like a big garden. 从山顶上看,这个城市就像一个大花园。 Accepted by the party, he decided to devote his life to the cause of the party. 入党以后,他决定献身于党的事业。