老师麻烦帮忙看下这个句子,谢谢~ Herzog's feature films often seem the by product of some transformative,often traumatic experience undergone by the director and his crew.此句后一个often后面的句子的结构我不明白啊,从undergone by这里很明显可以看出是个被动语态,可为什么没出现be动词啊,这个句子主语是herzog's feature films吗,如果是,很明显差一个be动词,亦或者它是some transformative的同位语?高人解答,多谢!