定语从句中一定有先行词吗?

rt
求原因解释

why don't you put your number where it can be seen?是定语从句吗?

是的,一般有.所谓先行词,其实是定语从句所修饰的词或短语或句子.因为定语从句,顾名思义,是指整个从句作定语,因此必然是修饰某一名词或代词或类似它们功能的词的.
注意,as,which等在非限制性定语从句中可修饰整个主句,这时你可把整个主句理解成是先行词.如: As we know, smoking is harmful to one's health.
The sun heats the earth, which is very important to us.

这是一定的。先行词是定语从句修饰的名词或代词，没有先行词，那定语从句没用无用武之地了。只是有一种特殊情况要注意，在非限制性定语从句中，有时先行词变成了一个句子。

是的绝大多数都是要有名词代词来做先行词！ 但也有少数情况，比如which,as是指整句话！ he said he got top prize,which was not true.which 指他获得头奖这件事。 as we all know,the sun rises from the east. as 指☞后边说得太阳☀从东边出来。