He was found injured at the foot of a cliff.他被发现在山岩脚下受了伤。

解答：这里的“injured”为形容词作主语补足语。

句子语法结构分析如下

He 【主语】//was found 【谓语动词】//injured 【主语补足语】//at the foot of a cliff【地点状语】.

他被发现在山岩脚下受了伤。

injured  adj.受伤的;有伤的(英文解释：An injured person or animal has physical damage to part of their body, usually as a result of an accident or fighting.)

 The other injured man had a superficial stomach wound.另一名受伤男子是腹部的皮外伤。

Many of them will have died because they were so badly injured.  他们中很多人会因伤势过重而死亡。

【1】主动结构:A find B injured “A 发现B受伤了”

People found him injured at the foot of a cliff.人们发现他在山岩脚下受了伤。

【2】被动结构:B be found injured (by A) B被(A)发现受伤了”

He was found injured at the foot of a cliff.他被发现在山岩脚下受了伤。