【关于定语从句中只用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，而“that”作为关系代词在定语从句中的使用有其特定规则。虽然“which”和“who/whom”在很多情况下也可以用于引导定语从句，但在某些特定情况下，只能使用“that”。本文将总结出定语从句中只用that的七种常见情况，帮助学习者更准确地掌握这一知识点。
一、定语从句中先行词是不定代词时
当先行词是“all, everything, anything, nothing, something, little, much”等不定代词时，通常只能用“that”。
| 先行词 | 关系词 | 例句 |
| everything | that | I told you everything that happened. |
| nothing | that | There is nothing that can stop us now. |
二、先行词被最高级或序数词修饰时
如果先行词被“the best, the first, the last, the only”等修饰，必须用“that”。
| 先行词 | 关系词 | 例句 |
| the only thing | that | This is the only thing that I need. |
| the first time | that | It was the first time that I had seen her. |
三、先行词是“the one”或“the same”时
当先行词为“the one”或“the same”时，必须使用“that”。
| 先行词 | 关系词 | 例句 |
| the one | that | He is the one that we are waiting for. |
| the same | that | This is the same book that I read last week. |
四、先行词指人又指物时
当先行词既指人又指物时，只能使用“that”。
| 先行词 | 关系词 | 例句 |
| the man and the dog | that | The man and the dog that were in the park were lost. |
五、关系代词在从句中作宾语时（非正式语体）
在口语或非正式语体中，当“that”在从句中作宾语时，可以省略，但若不省略，则只能用“that”。
| 先行词 | 关系词 | 例句 |
| the book | that | I read the book that you gave me. |
六、当从句中已有疑问词时
如果定语从句中已经包含“what, when, where, why, how”等疑问词，那么“that”是唯一可选的关系词。
| 先行词 | 关系词 | 例句 |
| the reason | that | That’s the reason that he left. |
| the time | that | I remember the time that we met. |
七、在强调句型中
在强调句型中，无论先行词是人还是物，都必须使用“that”。
| 先行词 | 关系词 | 例句 |
| my father | that | It is my father that I admire most. |
| the house | that | It is the house that we bought last year. |
总结表格
| 情况 | 先行词类型 | 关系词 | 说明 |
| 1 | 不定代词 | that | all, everything, nothing 等 |
| 2 | 最高级或序数词 | that | the best, the first, the only 等 |
| 3 | the one / the same | that | 表示唯一性或同一性 |
| 4 | 既指人又指物 | that | 避免混淆 |
| 5 | 宾语位置（非正式） | that | 可省略，但可用 |
| 6 | 含疑问词 | that | what, when, where 等存在时 |
| 7 | 强调句型 | that | 强调结构中固定使用 |
通过以上七种情况的总结，我们可以更清晰地理解在哪些场合下只能使用“that”来引导定语从句。掌握这些规则有助于提高英语写作和表达的准确性，避免常见的语法错误。