as 做关系代词，是否可以引导前面 整个句子（我对as用法小结）

judge0dee

如题
我对AS 小小的总结，欢迎拍砖

1）做conj
 表示“像...一样”
        “当...的时候”
         “因为”
         “虽然”

2）做adv.
       as...as 中的第一个as ,表示“一样地”
       such as 表示“举例”

3）做pron.
    引导关系代词
     as 在从句中可以做主语、表语、宾语
   通常放在 the same, as, such 之后引导关系从句
    例子：  I need as many books as are required
                as 指代books

  As we kown, the earth is round(这个句子中as 指代后面整个句子对吗？）

求高手指点，看懂as 的用法对比较题很有帮助，急求！！

eb1forever

白勇第二章：as可以做指代词，代替简单主句。

wellsli

我手打一下manhattan上AS的用法：
conjunction as appears with a clause. it has three uses:
Duration As: AS i strolled to the store, i smelled the air.(=while,during)
Causation As: i will not tell you, AS you already know.(=since,because)
Comparison As: you should walk AS she wants to you to.(=in the same way)

Preposition As is used with a noun or noun phrase.it also has three uses:
Function As: AS your leader, i am in charge.(= in the role of)
Equation As: i think of you AS my friend.(= you are my friend)
Stage As: AS a child, i thought i could fly.(= when i was)

这里manhattan还说了 AS做连词可以加短语，且AS做介词时没有“like”的意思
其实我自己也不是非常明白AS we known中AS的用法，还有Equation as的用法，这里也希望NN来帮忙解读

希望对你有帮助..