【不定式是什么】在英语语法中，“不定式”（Infinitive）是一个非常基础且重要的概念。它由“to + 动词原形”构成，是动词的一种非限定形式，通常用来表示动作或状态的抽象意义。虽然“to”有时被看作介词，但在不定式中，它更多地起到标记作用，表明该动词是作为动词使用。
一、不定式的结构
| 结构 | 例子 |
| to + 动词原形 | to go, to eat, to write |
二、不定式的功能
不定式在句子中可以充当多种成分，主要包括：
1. 作主语
- To learn English is important.
- To win the game is our goal.
2. 作宾语
- I want to eat.
- She decided to study abroad.
3. 作表语
- My dream is to become a doctor.
- His job is to teach students.
4. 作定语
- I have a book to read.
- The man to meet you is my teacher.
5. 作状语
- He went to the store to buy some food.
- She studied hard to pass the exam.
6. 作补足语
- I saw him go out.
- They asked me to help them.
三、不定式的时态与语态
| 时态/语态 | 结构 | 例子 |
| 一般式 | to + 动词原形 | to eat, to write |
| 完成式 | to have + 过去分词 | to have eaten, to have written |
| 被动式 | to be + 过去分词 | to be seen, to be told |
| 完成被动式 | to have been + 过去分词 | to have been seen, to have been told |
四、常见错误与注意事项
1. 忽略“to”
- 错误：I want eat.
- 正确：I want to eat.
2. 误用介词
- 错误：I look forward to see you.
- 正确：I look forward to seeing you.
3. 不定式与动名词混用
- Some verbs are followed by either a gerund or an infinitive, but meaning may change.
- I remember to lock the door.（记得去做某事）
- I remember locking the door.（记得做过某事）
五、总结
| 内容 | 说明 |
| 不定式定义 | 由“to + 动词原形”构成，表示动作或状态的抽象意义 |
| 常见功能 | 主语、宾语、表语、定语、状语、补足语 |
| 时态变化 | 有主动和被动、一般和完成等形式 |
| 注意事项 | 避免遗漏“to”，注意与动名词的区别 |
通过理解不定式的结构和用法，可以帮助我们更准确地表达思想，提高英语写作和口语的准确性与自然度。