定从中as的用法

1.非限制性定语从句中,as用来代指整个主句,可以翻译为“就像/正如...”.
它所引导的定语从句可以放在主句句首/句中/句尾.
此用法和which类似.
如：As we all know,the sun is bigger than the earth.
As is known to us all,the sun is bigger than the earth.
2.在限制性定语从句中,如果先行词被such/so/such/so/the same修饰时,则关系代词一般采用as.
如：This is the same bike as I bought yesterday.
I haven't bought such a book as you showed me just now.

1、as用作介词时，意为“作为，当作”+名词，如：
They treated us as honoured guests.
As a monitor, you must do better than others.
2、as用作副词时，意为“同样，一样”用在“as…as”结构中，否定式“not as/so…as”，如：
Is it as difficult as ...

例2. as可引导非限制性从句，常带有