我想请问.
定语从句中的中心词是什么意思? 在句中有什么作用?
中心词和先行词有什么区别呢?~

还有.就是as是不是只能够引导限制性定语从句呢?

1.我这是第一次听说中心词，我只知道在复合句中,修饰名词或代词的从句叫定语从句,也叫形容词性从句。被修饰的名词或代词叫先行词。
2.as不仅可以引导限制性定语从句而且可以引导非限制性定语从句。
⑴as 可以引导限制性定语从句，但先行词前通常出现the same，as ，such，so修饰先行词，as用作关系代词在定语从句中做主语或宾语。例如：
It’s the same person as we wanted to find yesterday.
Such girls as he knows are good at English .
⑵as引导非限制定语从句可以放在主语之前、之中或之后，经常用于as we know ，as is reported ,as is said above, as is known to all 等结构中，as 含有“正如，正像”之意。如：
As you know , water is a liquid.
As is known to all ,he is the best students in our class .
As we all know ,he studies very hard .
你到我的共享资料里去下载有关定语从句的资料吧！希望对你学习有帮助！