学员疑问：
The liver cells in the donor organ are washed out with a detergent that gently strips away the liver cells, leaving behind a biological scaffold of proteins and extracellular architecture that is very hard to duplicate synthetically. 这个长句有一点费解，请帮我细致分析一下。

老师解答：

先抓主干：The liver cells （in the donor organ） are washed out [with a detergent].（供体器官中的肝细胞被用洗涤剂洗掉。）

in the donor organ：介词短语作后置定语，修饰 The liver cells。

with a detergent：介词短语作方式状语，修饰 are washed out。

第一层修饰：that gently strips away the liver cells 定语从句修饰 detergent ，意思是“这种洗涤剂能温和地剥离肝细胞”

第二层修饰：leaving behind...现在分词短语作结果状语，逻辑主语是前面的整个动作/洗涤剂作用过程：意思是“留下一个由蛋白质和细胞外结构构成的生物支架”

leaving behind 的宾语是：a biological scaffold of proteins and extracellular architecture

中心词：a biological scaffold（生物支架）

of proteins and extracellular architecture介词短语作后置定语，说明支架由什么构成

第三层修饰：that is very hard to duplicate synthetically定语从句，修饰前面的名词。

点评分析：

that is very hard to duplicate synthetically定语从句到底修饰前面的哪个名词？

从语法位置看，that 紧挨着 extracellular architecture，形式上最近先行词是 architecture。

但从语义看，真正“很难人工合成复制”的是整个 biological scaffold（生物支架），而不只是细胞外结构。因此更合理的理解是：这个定语从句修饰 a biological scaffold，说明这个生物支架很难用合成方法复制。