【过去完成时的结构】过去完成时是英语中一种重要的时态，用于描述在过去某一时间或动作之前已经发生的事情。它常与另一个过去时态的动作相配合，表示“先发生”的动作。掌握过去完成时的结构，有助于更准确地表达时间顺序和事件之间的关系。
一、过去完成时的基本结构
过去完成时由“had + 过去分词”构成。其基本结构如下：
| 人称/数 | 肯定句结构 | 否定句结构 | 疑问句结构 |
| I | I had done | I had not done | Had I done? |
| You | You had done | You had not done | Had you done? |
| He/She/It | He/She/It had done | He/She/It had not done | Had he/she/it done? |
| We | We had done | We had not done | Had we done? |
| They | They had done | They had not done | Had they done? |
二、过去完成时的用法
1. 表示在过去某一时间点之前已经完成的动作
- 例句：When I arrived, she had already left.
（当我到达时，她已经离开了。）
2. 在叙述过去的事件中，说明某个动作发生在另一个过去动作之前
- 例句：He said that he had finished his work before he went to bed.
（他说他在睡觉前已经完成了工作。）
3. 在条件状语从句中，表示对过去的假设
- 例句：If I had known, I would have helped you.
（如果我早知道的话，我会帮助你的。）
三、过去完成时的常见错误
1. 混淆一般过去时与过去完成时
- 错误：I saw him before he came.
- 正确：I had seen him before he came.
（在我见到他之前，我已经见过他了。）
2. 忘记使用过去分词
- 错误：She had go to the store.
- 正确：She had gone to the store.
3. 误用助动词
- 错误：Had you eat breakfast?
- 正确：Had you eaten breakfast?
四、总结
过去完成时是一种用来表达“过去某时间之前已完成动作”的时态，结构为“had + 过去分词”。它常用于描述两个过去动作之间的先后关系，或在虚拟语气中表示对过去的假设。掌握其结构和用法，有助于提高语言表达的准确性与逻辑性。
| 项目 | 内容 |
| 时态名称 | 过去完成时 |
| 结构 | had + 过去分词 |
| 常见用法 | 描述过去某一时间前已完成的动作；叙述过去事件中的先后顺序 |
| 常见错误 | 混淆一般过去时、忘记使用过去分词、误用助动词 |
| 举例 | When I got home, my sister had already cooked dinner. |
