that which 定语从句的区别 定语从句什么时候只能用that? that
在英语定语从句中，只能用关系代词that的情况主要有下面内容八类，结合搜索内容归纳如下：
一、先行词为不定代词
当先行词是everything、nothing、something、anything、all、little、much、few、none等不定代词时，只能用that：
- 例句：
- There islittlethat the doctor can do.
- I refuse to accept the blame forsomethingthat was someone else’s fault.
二、先行词被特定限定词修饰
若先行词被the only、the very、the same、the last、the just、just the等强调性词语修饰时，只能用that：
- 例句：
- He isthe very manthat helped the girl out of the water.
- It isthe only bookthat he bought himself.
三、先行词被序数词或最高质量修饰
当先行词前有序数词（first、second等）或形容词最高质量（best、most等）时，必须用that：
- 例句：
- The first English bookthat I read was The Prince and the Pauper.
- Guilin is one ofthe most beautiful citiesthat I have ever visited.
四、先行词包含人和物
若先行词同时指人和物时，只能用that：
- 例句：
- He talked aboutthe men and booksthat interested him greatly.
- The thief handedeverythingthat he had stolen to the police.
五、主句以疑问代词开头
当主句是以which或who开头的独特疑问句时，为避免重复，从句用that：
- 例句：
- Which was the hotelthat was recommended to you?
- Who is the boythat is talking with Mary?
六、存在there be句型
在there be句型中，若主语为物，从句关系代词用that：
- 例句：
- There are three articlesthat I want to read.
- There is no meat in the storethat I want.
七、关系代词作表语
当关系代词在从句中作表语时，只能用that：
- 例句：
- She isn’t the womanthat she was in the past.
- Our school is no longer the onethat it used to be.
八、其他独特情况
- 先行词为the way或the reason时，若从句缺少状语，可用that代替关系副词（可省略）：
- It is the first time (that) I’ve seen such a wonderful building.
- 主句是强调句型（It is…that…）时，只能用that：
- It was the bookthat I lost yesterday.
以上八种情况需优先使用that，但需注意下面内容例外：
- 非限制性定语从句中不能用that（如：The tree,which is 400 years old, is famous.）；
- 介词后若需关系代词，用which/whom而非that（如：This is the roomin which he was born.）。
如需具体习题练习或例句分析，可参考相关语法教材或高考真题
