as、which引导的非限制性定语从句区别

Which、as引导非限制性定语从句区别

1、语义的区别

当主句和从句语义一致时，用as；

He made a long speech,as we expected.

当主句和从句语义转折不一致时，用which，

He made a long speech,which was unexpected.

2、位置的区别

看到句首一定用as，which 不可能放在句首。

as we all know,众所周知

as is mentioned above，正如上文所提到的

as often happens，正像经常发生的

as is often the case，正如通常的情况

As is well known，众所周知

3、含义的区别

as有“正如”的含义，which没有此含义。

As is well known，Shanghai is a big city．

Some of the roads were flooded， which made our journey more difficult．

4、否定句用which

Tom drinks a lot everyday,which his wife doesn’t like at all.

5、从句谓语是be或者联系动词时，用as、which均可；但从句

谓语是行为动词时则用which做主语： He married her, as/which was natural. He saw the girl, which delighted him.