there wew strange marks on the X-ray plates taken of the mum

作定语用的过去分词相当于形容词,其逻辑主语就是它所修饰的名词.及物动词的过去分词作定语,既表被动又表完成;不及物动词的过去分词作定语,只表完成.
过去分词短语用作定语时,一般置于其所修饰的名词之后,其意义相当于一个定语从句,但较从句简洁,多用于书面语中.
The concert given by their friends was a success.他们朋友举行的音乐会大为成功.
本题就是过去分词短语作定语,本来是take X-ray plates of the mummy,就是给木乃伊拍X光片.现在把宾语X-ray plates 提前,也就是X-ray plates 被拍,所以就是taken of the mummy,变成了···样的光片——给木乃伊所拍的光片
如果变成了完整的定语从句就是
there wew strange marks on the X-ray plates which was taken of the mummy.