请分析这句话,包括语法

题目

请分析这句话,包括语法
Its wool,which had been dyed black,had been washed clean by the rain!

答案

它（应该是前一句话里提到过的东西）被染黑的羊毛,已经被雨水冲得掉色了.
句子的主干是
Its wool had been washed clean by the rain.
which had been dyed black是定语从句,修饰wool
不过个人觉得had been washed clean by the rain似乎不应该用过去完成时.因为定语从句里面用得是过去完成时,表示过去的过去发生的事情,而主句再用过去完成时,逻辑上显得有点不对.这里可能用现在完成时has been washed更加合适.