为什么一些副词能做表语，一些不能做表语？？？？the sun is up中up副词，那she is beautifully中，这个beautifully不对呀？谁能解释下？
原则上说，用于系动词后作表语要用形容词，而不是副词。如：
他的英语很好。
误：His English is very well.
正：His English is very good.
这饭菜闻起来真香。
误：The dinner smells deliciously.
正：The dinner smells delicious.
但在以下情况，副词可用作表语（且主要是用于系动词be后作表语）：
1. 表示地点或位置的少数副词，如here, there, upstairs, downstairs, abroad, back等。如：
He asked if anyone was there. 他问那儿是否有人。
Are the children back yet? 孩子们回来了吗?
Neither of them is here. 他们俩都不在这里。
She was abroad all last summer. 她去年整个夏天都在国外。
The office that deals with passports is upstairs. 办护照的办公室在楼上。
If he was downstairs, why didn’t he answer the bell? 他要是在楼下，为何不开门呢?
2. 与介词同形的小品词有也可用作表语，如in, on, off, out, by, away, behind, up, down, over, through, around, round, below, inside, outside 等。
Make sure the lid is on. 确信要把盖子盖上。
The engagement is off. 婚约取消了。
The taxi is outside. 出租车在外面。
The grocery was below. 杂货店在下面。
The level of unemployment is down. 失业率在下降。
I phoned Sally but she was out. 我给萨莉打电话，可是她不在。
He hid the money when nobody was by. 附近没人时他把钱藏了起来。
By the time we arrived the meeting was over. 我们到达时，会议已结束了。
He was left in charge of the shop while the manager was away. 经理不在时，他负责这个商店。
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不是所有副词都可以做表语。只有部分副词可以。实在不行就强行记忆吧
本回答被提问者和网友采纳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名词短语作宾语,所以经常有介宾短语的说法
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）