定语从句中as和which

as和which都可以引导非限制性定语从句，先行词为整个主句或主句中的一部分内容，先行词在定语从句中作主语、宾语或表语，as与which均不可省略，有时两者可以互换。下面小编为大家分享定语从句中as和which，欢迎大家参考借鉴。

只用as而不用which：

一、当定语从句置于主句前面时：

例：As you see, the Chinese people are hard-working. (定语从句在句首)

你知道，中国人民是勤劳的。

注意下面句子的多种表达方法：

众所周知，月球每月绕地球转一圈。

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

2. The moon travels round the earth once every month, as/which is known to everybody.

3. It is known to everybody that the moon travels round the earth once every month.

is known to everybody is that the earth travels round the earth once every month.

(后两句属名词性从句范畴)

二、先行词做主语且定语从句为被动语态时：

此时，从句谓语通常为： be known, be said, be reported， be announced, be mentioned等。如果从句是主动语态，一般用which作主语。

例1：She has been absent again, as is expected.

她又缺席了，这在预料之中。

例2：Tom has made rapid progress, which makes me very happy.

汤姆进步很快，这使我很高兴。

另外，as常用在下列习惯用语中：as (it) seems likely, as (it) often happens, as (it) was printed out, as (it) was said earlier, as I remember (it), as I understand (it), as (it) appears, as it often the case, as anybody can see, as we have expected.

例1：Jack has won the first prize, as it often happens.

像往常一样，杰克得了一等奖。

例2：She has read widely in Romantic Literature, as it appears from her essay ·

她广泛涉猎了浪漫主义文学，这从她的文章中可以看出来。

只用which而不用as

一、关系代词代替前面主句中的宾语从句或定语从句的谓语动词后有复合宾语时：

例：I don't think that he will come to see me, which makes me sad.

我认为他不会来看我了，这使我伤心。

二、which一般用作实义动词的'主语，这时它所引导的从句与主句之间存在着逻辑上的因果关系时：

例：Tom was late for school again and again, which made his teacher very angry.

汤姆一次又一次上学迟到，这使得他的老师很生气。

三、当非限制性定语从句是否定句时：

例：He pretended not to know me, which I didn't understand.

他假装不认识我，我真不明白。

四、非限制性定语从句中的be动词不能省略时，用which反之用as.

例1：Jane told me she won the match, which was a lie.

简告诉我她赢了这场比赛，这是谎话。(was不可省略)

例2：As (was) planned, we met at the airport.

按照计划，我们在机场相见了。(was可省略)