(六)、定语从句与同位语从句

　定语从句相当于形容词，它对先行词起修饰、描述或限制作用，而同位语从句则相当于名词，它对其前面的词给予说明或作进一步解释，即说明该词所表示的具体内容。例如：

　The news that we heard is not true.(定语从句)

　The news that he won the prize is not true.(同位语从句)

　另：在"have no idea+从句"结构中，其从句都作idea的同位语。例如：

　I have no idea when she will be back.

(五)、定语从句中的先行词

　Is this book the one that you bought yesterday?

　Is this the book that you bought yesterday?

　第一个句子中，this book是主句的主语，the one 是先行词。在第二个句子中this是主句的主语，the book是先行词。一定要避免出现：Is this book that you bought yesterday?

(四)、定语从句与状语从句

　He found the books where he had put.

　He found the books in the place where he had put.

　第一个句子为状语从句，where he had put 作主句He found the books 的地点状语。第二个句子为定语从句，where引导从句修饰the place。

　This is such an interesting book that I'dlike to read it.

　This is such an interesting book as I'd like to read.

　第一个句子为结果状语从句，在结果状语从句中，it指代book,作read的宾语。第二个句子为定语从句，关系代词as指代先行词book的定语从句中read的宾语。

(三)、定语从句与并列结构

　He has two sons,neither of whom looks like him.

　He has two sons,and neither of them looks like him.

　I've got two sisters.Both of them are in Shanghai.

　第一个句子为定语从句，关系代词whom指代two sons,在定语从名中介词of的宾语。第二个句子为并列结构，由并列连词and连接，人称代词them指代two sons。第三个为两个独立的句子，两个句子中间用句号，两句开头的处一个字母都大写。

(二)、定语从句与强调结构

　It is the place where they lived before.

　It is in the place that they lived before.

　第一个句子为定语从句，where指代the place,在定语从句中作状语，第二个句子为强调结构，强调in the place,that没有意义，把in the place 放回后面句子，句子意思完整。

　Where is it that he found the lost watch?(强调句型，强调疑问副词where)。

　Where is the watch that he found yesterday.(定语从句，that指代the watch)

　 定语从句又称为关系从句，是最常见的从句之一，每年高考题对之均有考查。

(一)、定语从句中关系代词与先行词的一致性

　定语从句中关系代词一般应与它所指代的先行词的单复数保持主谓一致。例如：

　The students who were here just now are from No,2 Senior Middle School.

　但注意下列一组句子：

　He is the only one of the students who was here just now.

　He is one of the students who were here just now.

　如果"one of +复数名词"后跟有定语从句，一般情况下"one of"后的复数名词为先行词，但当one前有the only,the very,just the修饰时，先行词则为one。

2．As引导的非限制性定语从句的位置

　as引导的非限制性定语从句位置较灵活，可以位于主句前面．中间或后面，一般用逗号与主句隔开，但which所引导的非限制性定语从句只能放在主句之后。例如：

　(1) As is expected, the England team won the football match.

　(2) The earth runs around the sun, as is known by everyone.

1. 引导限制性定语从句和非限制性定语从句

　 (1)as多与such 或the same连用，可以代替先行词是人或物的名词。

　 (2)as 也可单独使用，引导非限制性定语从句，作用相当于which。例如：

The elephant’s nose is like a snake, as anybody can see.

　 (3)the same… that与 the same …as在意思上是不同的。

3.　先行词与定语从句隔离

　定语从句一般紧跟在先行词之后，但定语从句与先行词之间有时也会插入别的成分，构成先行词与定语从句的隔离。例如：

　1) This is the article written by him that Is poke to you about..

　2) He was the only person in this country who was invited

2．关系代词和关系副词的选择依据

　(1) 弄清代替先行词的关系词在从句中作什么成分,作状语的应选用关系副词，作主语．宾语或表语的可选用关系代词。