c. what 后面加名词
例：What money I have has been given to you.
B. as
as引导定语从句。既可引导限制性定语从句，也可引导非限制性定语从句。引导限制性定语从句一般是固定用法。如as…as, such…as, the same...as考试中经常考到。
例：Such a student as works hard were be sure to succeed.
as引导非限制性定语从句。as引导的定语从句修饰整个句子时，一定要和主句用逗号隔开，即非限制性定语从句，先行词就是它所修饰的整个句子，该从句可放在主句前、主句后或插入主句中，as在句中作主语或宾语。
例：As is so often pointed out knowledge is a two edge weapon which can be used equally for good or evil.
I was a boy which you know. which可以用as替换。
C. than 作为关系代词可以引导定语从句
例：More families consist of one parent households or two working parents; consequently, children are likely to have less supervision at home ____ was common in the traditional family structure .
A. than B. that C. which D. as
特点：
1) than作为关系代词引导词在从句中一般必须做主语或者作宾语。
2) than 前面的主句必须要有比较级
3) 比较级所修饰的名词就是than指代的对象
(2)定语从句里面关系副词的用法。
1)常用的关系副词：when, where, why
2) When引导定语从句的用法。
A. 先行词必须是表示时间的名词。
Or so the thinking has gone since the early 1980s, when juries began holding more companies liable for their customers’ misfortunes.
B. 如何区分when引导的定语从句和状语从句。用句子表示状语就是状语从句。例如：When I go to school, I will work hard.
从两方面区分：
When 引导的定语从句前一定有表示时间的名词;When 引导的状语语从句前没有有表示时间的名词。
从翻译的角度看如果是引导的定语从句可以不翻译。如果是状语从句就必须翻译成当……时候。
When=on which
Where
where=in which
where引导的从句先行词必须是表示地点的名词。例如：
I was born in Beijing where the Olympic games will be held.
先行词表示地点，不一定用where来引导。例如：
I have never been to Beijing, but it’s the place __.