一共有9个:who , whom , whose, that, which , when , where, why, as
⑴引导定语从句。 ⑵代替先行词在定语从句中充当一个成分。
判断先行词在定语从句中充当什么成分。根据充当的成分选择相应的引导词。
现行词前为all, everything, nothing, something, anything, little, much等不定代词时. 先行词前有:all, every, no, some, any, little, much, few等不定代词修饰时. 先行词被叙述词修饰时. 先行词被形容词最高级修饰时. 先行词前only, just, very, last有等修饰时. 先行词是表示人和物混杂的两个名词时. 主句是以who, which,开头的疑问句或先行词是疑问代词时. 在修饰时间、地点等先行词时,只有用that代替when, where等引导词。 例:I'll never forget the Sunday (that) you first arrived. Do you know anywhere (that) I can get a drink ? 先行词为reason, way (意为'方法')时,常用that 代替why, which, in which, 也可省略. 引导词在定语从句中作表语时,多用that引导. 先行词是主句表语时. 例:It is a dictionary that will help you a lot. 当主语以there be 开头时. 当先行词是数词时. 同一个复合句里有两个定语从句,一个用which,另一个通常用that.
reason后面的定于从句用why引导。 way 后面定语从句用in which 或that引导that可以省略。
as和which 都可以引导非限制性定语从句.都可以代替主句中的整个内容或某一成分. as 引导的非限制性定语从句可以位于句首,并常和know, see, expect等词连用.意为:'正 如...'.而which不能位于句首.
such... as the same... as so ... as..
the same...as 引导的定语从句指的是相同事物,强调同类.the same...that 引 导的定语从句指的是同一物. This is the same pen as I bought yesterday. (相同) This is the same pen that I borrowed from Mr. Li. (同一物)
whose 作定语,后面跟名词.一般有三种表示形式. 例: This is the dictionary whose cover has come off. = This is the dictionary the cover of which has come off. = This is the dictionary of which the cover has come off.
B. 名词性从句
It is + (名词、形容词、过去分词+ that ... It seems(mattes / happened) that...
★that在主语从句、表语从句、同位语从句中(除宾语从句)即使不充当成分, that 不能省。 ★在等表示命令、请求、建议等动词后的宾语从句中that不能省。 ★在6123结构中,引导宾语从句的that不能省。 ★由and或or所连接的两个宾语从句时,第一个从句中的that可以省;而第二 个从句中的that不能省。 ★that 引导的宾语从句,如果从句中还有其它状语从句,引导宾语从句的that 不能省。
定语从句: 由for which, why引导,引导词必须代替先行词在其从句中充当成 分.如:What is your reason why (for which) you were late? 同位语从句:由that引导,引导词在从句中不充当句子成分.如:The reason that he didn't come her this morning is not clear. 表语从句: 由that引导,在从句中不充当句子成分.如:The reason is that he doesn't like being laughed at in public.