定语从句缺主语用什么

定语从句是高考单选必考的重要考点，也是阅读中长难句常见的句型结构，同时也是提升写作表达的重要知识点。但是不少同学学习了很久，对于定语从句的掌握还是差强人意。今天就开始重点说一下定语从句的'基本用法。

要理解定语从句，首先就要理解什么是“定语”。“定语”是修饰名词的，也就是形容词，比如漂亮的，丑陋的，大的，小的……当定语太长，比如”穿着红衣服的那个漂亮的女孩，一个形容词无法担任起修饰名词的任务，此时就把定语变成一个句子，放在名词后面，所以定语从句一定是在名词之后的。

定语从句由三部分构成，名词（又叫先行词）+关系代词/关系副词+定语从句。

This is the house that I bough.

This is the house where I spent my childhood.

那究竟是要用关系还是关系副词，我们要做两件事情：

看定语从句的句子成分

看定语从句和名词的关系

定语从句的成分

　　缺主语

既然叫从句，它就是一个句子，句子就要有主谓宾。如果定语从句缺主语，那就要在定于从句前加上关系代词that/which/who充当主语， 前面的名词如果是人用that和who都可以，如果是物，用that和which

例子

This is the man who/that helped me.

I lost the book that/which cost me 100 yuan.

　　缺宾语

同缺主语的情况一样，前面的名词如果是人用that和who都可以，如果是物，用that和which，唯一不同的是关系代词作宾语时可以省略。

This is the man (who/that) I like.

I lost the book (which/that) he bought.

That和which既可以指人也可以指物，但是有四种情况下，关系代词一般用that

先行词既有人也有物

The writer and his novels that the article deals with are quite familiar to us.

先行词是all, little, much, none, the first

All that glitters is not gold.

先行词是不定代词something, anything, nothing, everything

I would much rather receive something that made me laugh.

先行词被any, only, all, every, 形容词和序数词修饰时，用that

Tell us all things that you know.

非限定性定于从句不用that

I became a single mother overnight, which is nothing like becoming famous overnight.