1.定语从句有语法规定如下:如果先行词被so,such,as和the same修饰时,则定语从句的关系代词一般使用as,以构成固定搭配so...as...,such...as...,as...as...和the same...as.
再如:This is the same bike as I lost yesterday.
I have bought so nice a car as you bought last week.
= I have bought such a nice car as you bought last week.
I'd like to have as big a house as you live in now.
2.该题中,关系代词as代替先行词word,在定语从句______is forbiden to apear in official media or documents at present充当主语.
因为word前面有so,所以关系代词使用as,而不用which/that.
3.这个语法比较难,希望楼主能理解使用.