where 不是“融合型关系副词”，而是一个普通的引导名词性从句的“连接代词”。

如果where 是“融合型关系副词”，就应该等于：the place where，前面不能加介词 in，不能说成： in the place where。

以下用法，where 才是“融合型关系副词”：

This is where I found my lost pen. = 

This is the place where I found my lost pen.

这就是我找到丢失钢笔的地方。

同样是 where he was，我们比较其作用：

He is still where he was.

He still stays where he was.

This is where he was.

where he was 用在be 之后是“表语从句”；用在不及物动词stay 之后，则是“地点状语从句”。以上两句，在表意上是一样的，只是在不同的动词之后，结构和作用不同而已。

第3句也是表语从句，但where 是“融合型关系副词”，等于the place where。

He is stil (in/at省略了） where he was.

以上是省略介词(at/in)where 引导的一个表语从句,不省略介词，则为介词宾语从句。

解答如下：

以上为“连接副词where”引导的“4种名词性从句”中的“表语从句”

(1)系动词be+where：引导表语从句(连接副词/融合性关系副词）

This is where he sleeps every day.

That's where the real danger lies.  

This iswhere he was killed.

That’s where Mother usually is at this time of day.

备注：下面是动词+宾语从句

He's locked in and nobody knows where the key is.  

For my part, I don't mind where we eat. 

Anybody will tell you where the bus stop is. 

He asked where there was a good hotel.

(2)名词+where ：引导定语从句（关系副词）

This is the place where he lived three years ago.

(3)动词+where：引导状语从句（从属连词）

We should go where we are needed most.

Don't leave it where the kids can get at it. 

He prefers to go where he can serve the people. 

Where there is a will, there is a way.