The nurse found a little boy in the corner of the room ,____and crying.

问题描述:

The nurse found a little boy in the corner of the room ,____and crying.
Afrightened B frightening C being frightened D having frightened

A
frightened是由动词的过去分词衍生出来的形容词.所以在这里可以当做非谓语动词使用,不加being.同样的句子还有:
Satisfied,she went out of the room.