Leave the things as they are.这是定语从句还是方式状语从句？

能否认为as是关系代词，指代things ?

回答如下：

以上为 AS 引导方式状语从句，按照他们原来的方式去保持这些东西的状态，意思就是别动这些东西

Leave the things as they are. 

别动这些东西

leave ...it/they are 使....处于他们原有状态

Leave the things as they are. 如果是方式状语从句，as为从属连词，在从句中并不担任成份，因此这个从句并不完整，are后面省略了成份，完整的写法是怎样的？as不会是复合代词做are的表语吧？

继续回答如下

as+主语+系动词be=按照（主语）现状/原样

as they are =按照（他们）现在的样

例如：

When in Rome,do as the Romans do.   
入乡随俗

State the fact as it is.   
照实讲来。

Balloons float in the air as boats float on water.

气球飘在空中如同船浮在水上一样。

Things were almost as they had been before.   

事情还像以前一样。

I like the house better as it is.

我更喜欢这个屋目前的样子。

Leave it as it is.

让它照现在的样子放在那儿〔顺其自然〕。

Take the world as it is.

世界就是这个样子，不要奢望什么。

I'm afraid you're simply painting the lily;the picture is good enough as it is. 我看你这样做简直是多余，这幅画本来已经够好了。

She looks forward,as does her secretary,to the completion of the building.   
她像她的秘书那样盼望工程竣工。

When in Rome,do as the Romans do.   
入乡随俗。