首先,第二句里里的are应该是were吧?
这两个句子错的太远,非动大手术不可.分次作状语,它的逻辑主语就是句子的主语
第1种改发：调整主句的主语
1.Arriving home,I found the door locked.
2.Looking out of the window,I saw lots of people.
第2种改法：当然了还可以用独立结构,这样手术小一些.
1.I arriving home,the door was found locked .
2.I looking out of the window,there were lots of people in the street.
第三种改法：不用分次形式,改用从句.
1.When I arrived home,the door was found locked.
2.When I looked out of the window,there were lots people.