武汉新东方夏令营提示，非限定性定语从句，既可以修饰先行词，也可修饰整个句子。它对其先行词没有限定、修饰的作用，只起补充、说明的作用。

      武汉新东方夏令营提示，非限制性定语从句与先行词关系不十分密切，只是对其作一些附加说明，不起限定制约作用。如果将非限制性定语从句省去，主句的意义仍然完整。
　一、一个明显标志
　　从句式上看，从句与主句之间有逗号隔开。
　　句子结构：先行词+逗号+关系词+定语从句
　　二、两个突出特征
　　1. 在非限定性定语从句中，不能用that，而用who， whom代表人，用which代表事物，why用for which替换。
　　2. 非限定性定语从句，既可以修饰先行词，也可修饰整个句子。它对其先行词没有限定、修饰的作用，只起补充、说明的作用。有时也用它来对全句进行补充、说明。即使将其去掉，也不会影响句子意思。
　　3. 两类关系词：
　　①关系代词。指物用which，指人用who或whom。
　　注意：whose+名词（指人/物）=the+名词+of which/whom=of which+the+名词
　　②关系副词（指时间when、地点where）
　　三、三项作用
　　1. 连接作用；2. 替代作用；3. 成分作用。
　　四、四步做题口诀
　　一看指人还是物， 二看介词在何处；
　　三看句中何功能， 四看是否属特殊。
　　技巧点拨：一看（先行词），二析（从句成分），三选（关系词），四思（特殊情况）。
　　1. 找先行词：先行词一般是名词和代词。
　　2. 看先行词在定语从句中所充当的成分是什么。
　　3. 定语从句中缺什么成分，我们就补充什么成分。判断成分要看先行词在定语从句中所起的作用是什么。
　　4. 分析情况是否特殊，特殊情况特殊对待。
　　五、五种成分
　　关系词可以在从句中充当主语、宾语、定语、表语、状语。
　　六、六个易错点
　　1. 非限制性定语从句通常不能用that引导。比如：
　　i like the book， which was bought yesterday.
　　i like the book which/that was bought yesterday.
　　2. 非限制性定语从句不能用why引导，要用for which代替why。如：
　　i had told them the reason， for which i didn’t attend the meeting.
　　3. 非限制性定语从句置于句首时，不能用which引导。关系代词as引导非限制性定语从句位置比较灵活，可以放主句前，也可以放主句后。如：
　　as i expected， he didn’t believe me.
　　she heard a terrible noise， which brought her heart into her mouth.
　　4. 在非限制性定语从句中，指物的关系代词作宾语时，只能用which；指人的关系代词作宾语时，只能用宾格whom，不能用who替换，也一定不能省略。
　　do you know tom， whom we talked about？
　　this book， which you can get at any bookshop， will give you all the information you need.
　　5. 当先行词是表示职业、品质、身份等含义的名词，做定语从句的表语时，从句必须用which引导，含有对比的意思。
　　jack’s brother is a policeman， which he isn’t.
　　6. 非限制性定语从句还能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。
　　he seems to have misunderstood what i meant， which greatly upsets me.
　　七、高考热点
　　1. as，which引导的非限制性定语从句的区别
　　①语义
　　当主句和从句语义一致时，先行词用as。
　　he made along speech， as we expected.
　　当主句和从句语义转折时，先行词用which。
　　he made along speech， which was unexpected.

②位置
　　as引导非限制性定语从句时，可以代主句的全部或部分内容。它常表示说话人的依据、态度、评论、看法等，有“正如、像”等意思。定语从句可以置主句句首、句中或句末。as后常接expect，know，report，say，see等动词的主、被动语态句。通常用下列句型：as is known to all， as is said， as is reported， as is announced， as we all know， as i expect。
　　③含义
　　as有“正如”的含义，which没有。
　　as is well known，shanghai is a big city.
　　some of the roads were flooded， which made our journey more difficult.
　　④否定句用which
　　tom drinks a lot everyday， which his wife doesn’t like at all.
　　⑤当主句和从句存在逻辑上的因果关系时，常用which
　　tom was always late for school， which made his teacher angry
八、易混点
　　1. 定语从句 vs 强调句型
　　it was nov.11， 2011 when they got married.（定语从句）
　　it was on nov.11，2011 that they got married.（强调句型）
　　2. 定语从句 vs 名词性从句
　　the fact that he told us is very surprising.（定语从句）
　　the fact that he had not said anything surprised everybody.（同位语从句）
　　3. 定语从句 vs 状语从句
　　she is such a good teacher as we all respect.（定语从句）
　　she is such a good teacher that we all respect her.（状语从句）
　　
　　1. i wish to thank professor smith， without help i would never have got this far.
　　a. who b. whose c. who d. which
　　2. it is the third time that she has won the race， has surprised us all.
　　a. that b. where c. which d. what
　　3. when deeply absorbed in work， he often was，he would forget all about eating or sleeping.
　　a. that b. which c. where d. when
　　4. the air quality in the city， is shown in the report， has improved over the past two months.
　　a. that b. it c. as d. what
　　5. they stood at the window， they could see was happening in the street.
　　a.where；all b.which；all
　　c.from where；what d.from which；that
　　6. his glasses， he was like a blind man， fell to the ground and broke its leg.
　　a. which b. with which
　　c. without which d. whose