nothing special是什么语法结构?比如it's nothing special.中其是什么结构?是形容词作后

是的.
something,anything,nothing,everything,someone,anyone ...等等叫复合不定代词,英语中,修饰复合不定代词的成分,要放在复合不定代词的后面,即定语后置.
再比如：something interesting
nothing to do
希望我的回答能够帮到你,