这句话为什么认为它是非限制性定语从句;As is often the case with children,TOm was copletely better by the time the doctor arrived.---- is often the case with the children,Tom was completely better by the time the doctor arrived.a.As b

为什么这句话是非限制性定语从句?Mr Smith from whom i have learned a lot is a famous scientist. 这句话为什么认为它是非限制性定语从句;As is often the case with children,TOm was copletely better by the time the doctor arrived.---- is often the case with the children,Tom was completely better by the time the doctor arrived.a.As b 什么是限制性定语从句,什么是非限制性定语从句? Her sister has become a layer.She wanted to be a layer.应合并为限制性定语从句还是非限制性定语从句?为什么? 英语：什么是非限制性定语从句? 什么是非限制性定语从句?急 什么是非限制性定语从句,用法 关于as a saying goes老师说,as a saying goes,no pains,no gains是非限制性定语从句,谁能分析一下句子结构,为什么是非限制性定语从句,哪个指代哪个啊? 也是说这是非限制性定语从句,请问从哪里看出?只因前面有逗号?,选 也是说这是非限制性定语从句, 请问从哪里看出?只因前面有逗号?, 选them, 为什么不行?何时用them? 什么是非限制性定语从句?和非限制性定语从句关系代词的用法? Mary received an invitation from her boss,------ came as a surprise答案填的是who,为什么不用which 我知道是非限制性定语从句,用who整句话的解释是什么? that 可引导非限制性定语从句么is that the exhibition_____we visited last year ?A where B that C in which Dthe one 答案是选B吧,但它是非限制性定语从句,that不是不可以引导非限制性定语从句么? I have a dream ,which fly in the sky.这句话有没有语法错误.这是非限制性定语从句,但是which后面的对不对.fly要不要改为flies 什么是非限制性定语从句?只能用which么? 什么是非限制性定语从句,有什么特征? 在英语中什么是非限制性定语从句 非限制性定语从句中关系代词一般要用which.she won the competition,which made the whole family very happy.什么是非限制性定语从句?怎么知道是非限制性定语?这一句话中不能用that吗? 问一道题（高中英语）Mr.Smith is a painter,________ I should also like to be in my teenage.A.thatB.itC.whoD.which答案是D．但是我觉得有点奇怪,这到底是定语从句还是非限制性定语从句?若是定语从句为什么会