Question

Here it is.此句中here是副词,副词怎么可以做表语呢?是不是只有形容词才可以做表语.

Answer 1

名词、形容词、副词、介词短语、不定式、句子（表语从句）都可以作表语,如：

I'm a student.He is honest.He is over there.He is at home.

My wish is to be a scientist.This is what I want.

Here it is.是全部倒装中的特殊情况.在全部倒装中,主语须是名词,如Here is your ticket.但当主语是代词时,主谓不倒装.