【什么时候介词后加动词原形】在英语学习中，很多学习者对“介词后是否加动词原形”这一问题感到困惑。实际上，介词后是否接动词原形，取决于该动词在句中的语法功能和固定搭配。以下是对这一问题的总结与归纳。
一、总结
1. 介词后通常不加动词原形：大多数情况下，介词后面应接名词或代词，而不是动词原形。
2. 某些固定搭配中，介词后可接动名词（V-ing）：例如 “look forward to” 中的 “to” 是介词，后面接动名词。
3. 介词后可以接动词不定式（to do）：如 “interested in doing” 中的 “in” 是介词，后面接动名词；但有些结构中，介词后也可接不定式，如 “depend on you to help”。
4. 介词后不能直接接动词原形：除非是特殊结构或固定短语，否则一般不成立。
二、表格总结
| 介词 | 后接内容 | 说明 | 示例 |
| to | 名词/代词 | 常见用法 | I am going to school. |
| to | 动名词（V-ing） | 固定搭配 | I look forward to meeting you. |
| to | 不定式（to do） | 特殊结构 | She depends on you to help. |
| in | 名词/代词 | 常见用法 | He is interested in music. |
| in | 动名词（V-ing） | 固定搭配 | He is good at playing piano. |
| with | 名词/代词 | 常见用法 | She came with her brother. |
| for | 名词/代词 | 常见用法 | This gift is for you. |
| about | 名词/代词 | 常见用法 | He talked about his trip. |
| about | 动名词（V-ing） | 固定搭配 | She is talking about going abroad. |
三、注意事项
- 介词 + 动名词（V-ing）：常见于一些固定短语中，如 “be used to”, “be good at”, “look forward to” 等。
- 介词 + 不定式（to do）：较少见，多出现在特定表达中，如 “the way to solve the problem”。
- 介词后不能直接加动词原形：如 “I am interested in go to the park.” 是错误的，应改为 “I am interested in going to the park.”
四、常见错误示例
- ❌ I am interested in go to the cinema.
✅ I am interested in going to the cinema.
- ❌ He is good at play football.
✅ He is good at playing football.
- ❌ She is looking forward to meet you.
✅ She is looking forward to meeting you.
通过以上总结可以看出，介词后是否接动词原形，主要取决于其后的成分是否为名词性结构。掌握这些规则有助于提高英语写作和口语的准确性。