过去完成时 (Past Perfect)

past -------- past point -------- now -------- future

            ↑
    在过去某时间点之前完成的动作

这种时态用于描述在过去某一时间点之前已经发生的动作或状态。

语法形式

过去完成时的构成是：主语 + had + 过去分词

• 肯定句：主语 + had + 过去分词

  • I had finished.
  • She had studied.

• 否定句：主语 + had not + 过去分词

  • I had not finished.
  • She had not studied.

• 疑问句：Had + 主语 + 过去分词？

  • Had you finished?
  • Had she studied?

应用场景

1. 表示过去某一时间点之前发生的动作

用于描述在过去某个时间点之前已经完成的动作。

示例：

• When I arrived home, she had already left. (当我到家时，她已经离开了。)
• By the time we got to the cinema, the film had started. (当我们到达电影院时，电影已经开始了。)

2. 表示"非真实"的过去

用于虚拟语气中，表示与过去事实相反的假设。

示例：

• If I had known about the meeting, I would have attended it. (如果我知道有会议的话，我就会参加了。)
• I wish I had studied harder when I was young. (我希望我年轻的时候学习更努力。)

3. 过去的经历或状态

用于描述在过去某个时间点之前的经历或状态。

示例：

• I had never seen such a beautiful sunset before that day. (在那天之前，我从未见过如此美丽的日落。)
• She had lived in Paris for ten years before she moved to London. (在搬到伦敦之前，她在巴黎住了十年。)

与其他时态的对比

过去完成时 vs 一般过去时

过去完成时强调在过去某个时间点之前发生的动作，而一般过去时则只是表示过去发生的动作。

示例：

• When I arrived (过去时), the meeting had already finished (过去完成时). (当我到达时，会议已经结束了。)

过去完成时 vs 现在完成时

过去完成时是以过去某个时间点为参照点，而现在完成时是以现在为参照点。

示例：

• I have finished my homework now. (现在完成时 - 现在已经完成)
• I had finished my homework when my mother came back. (过去完成时 - 在母亲回来之前已经完成)

常见用法和例句

1. 使用时间连接词

常与 before, after, when, by the time 等时间连接词一起使用：

• After he had finished work, he went home.
• By the time we arrived, they had left.

2. 表达遗憾或后悔

常用于 wish 从句或 if only 结构：

• I wish I had learned to swim when I was younger.
• If only I had listened to your advice.

3. 描述过去的过去

用于描述在过去某个时间点之前发生的事情：

• The house was empty. The burglars had taken everything.
• When we got to the station, the train had already left.