非限定性定语从句是英语语法中从句的一种，是定语从句的分支之一。而关于非限定性定语从句的引导词有哪些呢？

今天和小编一起重点来看看“介词+关系代词”引导的非限制性定语从句：

首先，讲讲什么是非限制性定语从句？

非限定性定语从句起补充说明作用，缺少也不会影响全句的理解，它与主句往往用逗号隔开。

“介词+关系代词”引导的非限制性定语从句指的是：在介词后引导非限制性定语从句。

关系代词which有时并不代表主句中某一确定的词，而是概括整个主句的意思。

介词的选择取决于它与先行词的搭配或与从句中谓语动词的搭配。

as it is known to all (that...) (as 做状语从句连词，是状语从句, 可以加that)
与 as is known to all (as做主语，是定语从句)
与 it is known to all that... (主语从句，it是形式主语)

即：

As is widely known, the moon is closer to the us than the sun.(定从)
= That the moon is closer to the us than the sun is widely known.(主从)
= It is widely known that the moon is closer to the us than the sun.(主从)
As it is known to everyone, I thought you knew about it too.(状从)

例句：

They were short of sticks to make frames for the climbing vines，without which the yield would be halved.
他们缺搭葡萄架的杆儿，没有它们产量会减少一半。

They thanked Tom，without whose support they would not have succeeded.
他们对汤姆表示了感谢，因为没有他的支持他们就不会成功。

These new neighbors，to whom I was introduced yesterday，have come here from Beijing.
这些邻居是北京来的，昨天我被介绍同他们认识了。

好了，以上就是“介词+关系代词”引导的非限制性定语从句的介绍，还请同学们在日常的学习中一定要勤加练习，在具体的句子中加以理解，一切问题就可以迎刃而解了。