【定语从句只用that的七种情况】在英语学习中，定语从句是一个非常重要的语法点。在使用关系代词时，很多同学常常混淆“which”和“that”的区别。实际上，在某些特定情况下，只能使用“that”，而不能使用“which”。掌握这些规则有助于提高写作和口语的准确性。
以下是定语从句中只用that的七种常见情况：
一、先行词是不定代词时
当先行词是all, everything, anything, nothing, something等不定代词时，只能用“that”。
| 先行词 | 关系代词 | 例句 |
| everything | that | I told you everything that happened. |
| nothing | that | There is nothing that can stop us now. |
二、先行词是疑问代词时
当先行词是who, which, what等疑问代词时，只能用“that”。
| 先行词 | 关系代词 | 例句 |
| what | that | I don’t know what that is. |
| who | that | The man that spoke to me was very polite. |
三、先行词被序数词或最高级修饰时
如果先行词被first, second, last, best, worst等词修饰，只能用“that”。
| 先行词 | 关系代词 | 例句 |
| first | that | She is the first person that I met in this city. |
| best | that | This is the best movie that I have ever seen. |
四、先行词被only, all, any, few, little等词修饰时
当先行词被only, all, any, few, little等限定词修饰时，通常用“that”。
| 先行词 | 关系代词 | 例句 |
| only | that | That’s the only book that I need. |
| all | that | All that glitters is not gold. |
五、先行词既有人又有物时
当先行词同时指人和物时，只能用“that”。
| 先行词 | 关系代词 | 例句 |
| people and things | that | The people and things that we saw were amazing. |
六、在非限制性定语从句中不使用that
虽然这不是“只用that”的情况，但需要特别注意：非限制性定语从句中不能使用“that”，只能用“which”。因此，在限制性定语从句中才可能使用“that”。
| 类型 | 关系代词 | 说明 |
| 限制性 | that | 强调信息不可省略 |
| 非限制性 | which | 补充说明，可省略 |
七、在强调句型中
在It is...that...结构中，只能使用“that”。
| 结构 | 关系代词 | 例句 |
| It is...that... | that | It is he that broke the window. |
总结表格
| 情况 | 先行词示例 | 关系代词 | 说明 |
| 不定代词 | everything, nothing | that | 只能用that |
| 疑问代词 | what, who | that | 只能用that |
| 序数词/最高级 | first, best | that | 只能用that |
| 被限定词修饰 | only, all, any | that | 常用that |
| 人和物并存 | people and things | that | 只能用that |
| 强制性定语从句 | 无具体示例 | that | 在强调句中使用 |
| 非限制性定语从句 | 无具体示例 | which | 不用that |
通过掌握这七种情况，可以更准确地判断在哪些语境下应该使用“that”而不是“which”，从而避免常见的语法错误。建议多做练习题，结合实际语境进行理解和应用。