请问,非谓语动词里面,什么时候有done前有be什么时候没有be

做主语和宾语时要有be
Being punished before the class is my great shame.
i am afraid of being punished before the class.
做定语状语和补语时省略be
Finshed in a hurry,the work is not perfect.
i found the work done in a hurry.
The work done in a hurry is not perfect.