不是所有副词都可以做。只有部分副词可以。实在不行就强行记忆吧

1、大部分副词小品词（即与介词同形的副词）都可以用作表语（以下大写表示）.
Mary was DOWN with a slight fever.
The light is still ON.
I'll be ALONG in a minute.
Are the Children BACK yet?
H'll be ROUND this afternoon.
Are you THROUGH (with your work)?
Is Staley ABOUT?
He hid the jewels when nobody was BY.
The storm was OVER before the morning.
He isn't UP yet?
Her office is just ABOVE.
His leave is UP tomorrow.
We're BEHIND in our plan.
I must be OFF now.
2、其他常作表语的副词
back,home,away,here,there,upstair,downstair,abroad
3、提高
介词与副词的区别
介词后面直接跟名词或作宾语,所以经常有的说法
副词后面不直接跟名词或名词短语作宾语,没听说过副宾短语的
例：
1）in the room（in是介词）
2）Come in.（in是副词）
3）get on the bus（on是介词）
4）Come on.（on是副词）