he will not do so for long,for mercifully the public have the good sense not to buy the inferior art

题目

he will not do so for long,for mercifully the public have the good sense not to buy the inferior article more than once.if you see an article consistently advertised,it is the surest proof i know that the article does what is claimed for it,and it represents good value.
这一段话中的what引导的宾语从句不明白里面的结构是什么?只知道大概what做主语,但不知道what指代什么?is claimed是谓语吧?for it是状语吗?直译的话：事情认为是商品.我翻译的肯定不对啊?到底what的从句该怎么翻译啊?
能不能把从句变成主动语态,说说这个从句是怎么变过来的.

答案

the article does what is claimed for it 这个商品能做到所宣称的
is claimed是谓语被动语态,for it是状语.还原成主动语态,就是：
the article does what they claimed for it
关系代词引导宾语从句时,不需要指代其它名词.如：
I like what you said.
You work with whoever is available.