[名师点津]　(1)非限制性定语从句可将整个主句作为先行词， 对其进行修饰， 这时从句谓语动词要用第三人称单数。

　　(2)非限制定语从句中，不用why引导，用for which代替why。

　　He has been busy with his work the whole holiday, which has made his girlfriend unhappy.

　　 他一整个假期都忙于工作，这令他的女朋友很生气。

　　The reason, for which he was absent from the meeting, wasn't given.

　　他为何缺席会议，没有给出任何理由。

　　[即时演练2]　用恰当的关系词填空

　　①Yao Ming, as you know, is an excellent basketball player.

　　②I wish to thank Professor Smith, without whose help I would never have got this far.

　　③(2013·天津高考改编)We have launched another man­made satellite, which is announced in today's newspaper.

　　④(2012·浙江高考改编)Ellen was a painter of birds and of nature, who,_for some reason, had withdrawn from all human society.

　　三、as 与which引导非限制性定语从句时的区别

as which 指代 引导从句只能指代整个主句的内容 引导从句既可指代整个主句的内容，也可指代主句的一部分 位置 可位于主句之前，之中或之后 引导从句不能置于主句之前 意义 正如 这，那 功能 连接上下文，表达说话人的观点、看法，并指出主句内容的根据或出处等 引导的从句在意义上相当于一个并列句 　　As we all know, the earth moves around the sun.

　　众所周知，地球围绕太阳转。

　　The singer, as was expected, achieved a great success.

　　正如所期盼的，这位歌手取得了巨大成功。

　　 Catherine will attend a friend's wedding, which she is busy preparing for now.

　　凯瑟琳将参加一个朋友的婚礼，现在她正在为此做准备。

　　[即时演练3]　选词填空(as/which)

　　①(2014·四川高考改编)Until now, we have raised 50,000 pounds for the poor children, which is quite unexpected.

　　②(2013·山东高考改编)There is no simple answer, as is often the case in science.

③(2013·江苏高考改编)The president of the World Bank says he has a passion for China, which he remembers starting as early as his childhood.