过去分词短语做原因状语的例句:
Born in a poor family, he had to work when he was a child. 由于出身贫寒,小时候他就不得不工作。(赵俊英:《现代英语语法》p.467)
The audience, greatly affected by his speech , all voiced their support for the proposal . 听众被他的演说深深感动,所以都表示支持这项建议。(同上)
His car broken down , he had to walk. 他的车坏了,所以他只好走路。(龚亚夫:《新编高中英语语法》普及版p.265)
过去分词短语作伴随状语的例句:
He came in , followed by his wife . 他走了进来,后面跟着他的妻子。(龚亚夫:《新编高中英语语法》普及版p.265)
I sat until after eleven , absorbedin a book . 我一直坐到11点之后,埋头读一本书。(赵俊英:《现代英语语法》p.436)
从上述例句可以看出,过去分词短语作伴随状语时,分词表示的动作和句中谓语动词所表示的动作是同时发生的;过去分词短语作原因状语时,分词表示的动作是在句中谓语动词所表示的动作之前发生的。所以,下面句子中的过去分词短语应该是原因状语:
The tiger escaped from the zoo, frightened by the humans.