which修饰句子

which 可以引导非限制性定语从句。关系代词 which（只用 which，不用 that）在非限制性定语从句中所指代和修饰的可以是主句中的先行词名词、句中某一部分、或整个主句，在从句中作主语、宾语、或表语。which修饰整个句子，常用于非正式场合和口语，作为非限制性定语从句，在which前要加逗号。

• which 指代句中某一部分

Peter drove too fast.That was dangerous.

Peter drove too fast, which = (drove too fast) was dangerous.

• which 指代句子整体

Tom was late. That surprised me.

Tom was late,which= (Tom was late) surprised me.

as修饰句子

as也可作为关系代词修饰整个句子，此时用法和which一致。

Tom was late. That surprised me.

Tom was late, as surprised me.

as和which的差别

• as引导非限制性定语从句时，位置比较灵活，可位于主句之前，也可位于主句之中或之后，而which引导非限制性定语从句只能位于主句之后，不能谓语主句之前。

As is known to everybody,the moon travels round the earth once every month.

Which is known to everybody, the moon travels round the earth once every month.

• as引导非限制性定语从句常有“如同……那样”的含义,which常用于表达对主句的评论和因果关系

she is very careful,as her work shows.（表达正如...那样）

The elevator is out of order,which is too bad.(表达评论）

• as引导非限制性定语从句时在意义上不可与主语相悖

Mummy treats me like a baby, which I can't bear.

Mummy treats me like a baby, as I can't bear.

• which引导非限制性定语从句作从句里面的介词宾语时，介词可以提到which前

• as常用固定搭配（被动与主动形式）