There was a stanger (stand)_at the door

There was a stanger (stand)_at the door

与被修饰词为主动关系且表示正在进行的动作.如：
1.There were about 200 children studying in the art school.有大约二百个孩子在这所艺术学校学习.
2.Who is the woman talking to our English teacher?
正在和我们英语老师谈话的那位妇女是谁?

There was a stranger standing at the door.
有个陌生人站在门口