【关于定语从句中只用that的七种情况】在英语语法中，定语从句是用来修饰名词或代词的一种从句结构。在大多数情况下，关系代词“which”和“that”都可以用于引导定语从句，但在某些特定情况下，只能使用“that”，而不能使用“which”。为了帮助学习者更好地掌握这一规则，本文将总结出定语从句中只用that的七种常见情况，并以表格形式进行清晰展示。
一、
1. 当先行词是不定代词时：如“everything, something, nothing, anything”等，通常只能用“that”引导定语从句。
2. 当先行词是最高级或序数词时：如“the first, the best, the most important”等，一般使用“that”。
3. 当先行词被形容词最高级修饰时：例如“the most interesting book that I have ever read”。
4. 当先行词是整个句子时：即从句是对前面整个句子内容的说明，此时用“that”更合适。
5. 当关系代词在从句中作宾语且前面有介词时：如果介词放在关系代词前，只能用“that”。
6. 当先行词是人和物混合时：如“the man and the car that were involved in the accident”。
7. 当从句中有“all, everything, nothing”等词时：这些词后面通常接“that”引导的定语从句。
以上七种情况是英语学习中较为常见的“只用that”的定语从句结构，掌握这些规则有助于提高语言表达的准确性与地道性。
二、表格总结
| 情况 | 先行词示例 | 例句 | 说明 |
| 1 | everything, something, nothing, anything | Everything that he said was true. | 不定代词作先行词时，只能用“that”。 |
| 2 | the first, the best, the last | The first movie that I saw was exciting. | 当先行词是最高级或序数词时，用“that”。 |
| 3 | the most important, the least possible | This is the most important thing that we need. | 被形容词最高级修饰的先行词，常用“that”。 |
| 4 | 整个句子 | That he failed the exam surprised everyone. | 当从句是对整个句子的说明时，用“that”。 |
| 5 | 带有介词的宾语 | The book that I borrowed from the library is missing. | 如果介词前置，只能用“that”。 |
| 6 | 人和物混合 | The people and the cars that were at the scene were questioned. | 当先行词包含人和物时，用“that”。 |
| 7 | all, everything, nothing | All that she said was helpful. | 当先行词是“all, everything, nothing”等时，用“that”。 |
通过上述总结和表格，我们可以更清晰地理解在哪些情况下必须使用“that”来引导定语从句。掌握这些规则不仅有助于提高语法准确性，也能增强英语写作和口语表达的自然度。建议在实际练习中多加应用，逐步形成语感。
