3.The question that puzzles them is____they can get rid of t

跟你把D还原一遍： They can get rid of the air pollution in the area (in this way). 如果对方式状语in this way进行强调，则该强调句型为： It is in this way that they can get rid of the air pollution in the area. 该句的特殊疑问句（即对in this way划线提问）为： How is it that they can get rid of the air pollution in the area? 该句如果做一个句子的宾语从句，则变成陈述句序为： ... how it is that they can get rid of the air pollution in the area 补充： 1. It was true that what Alice did surprised her mother. that what Alice did surprised her mother是主语从句，前面的It是形式主语； 该主语从句中，主语为what Alice did，谓语是surprised，her mother是宾语。 所以这个主语从句that what Alice did surprised her mother中另含有一个主语从句what Alice did，当然就出现两个引导词。 that是大的主语从句引导词，而what是其内的那个小的主语从句的引导词。 2. What Alice did surprised her mother. 此句中，主语为（从句）What Alice did，谓语是surprised，宾语是her mother. 只有一个从句，也自然只能有一个引导词，that不能又放进去。 3. I could see that what he did was unconscionable. 主句主语是I，谓语是could see，that what he did was unconscionable是宾语（从句）。 该宾语从句中，主语是（从句）what he did，谓语是系表结构was unconscionable. 所以这个宾语从句的主语又是一个主语从句。 既然有两个从句，当然就出现了两个引导词。 这种题目楼主之所以搞不清楚，是因为楼主对句子结构划分掌握不够，应该结合句意对句子进行结构划分。

没错。 what Alice did这个主语从句做主语从句(that) what Alice did surprised her mother中的主语。