用于描述在过去某个时间点之前已经发生或完成的动作或状态。它强调过去某一动作或状态在另一个过去时间点之前已经发生或完成。
| 主语 + had + done(过去分词) |
- She had already finished her homework before the party started.（派对开始前，她已经完成了她的家庭作业。）
- They had already left when we arrived at the cinema.（当我们到达电影院时，他们已经离开了。）
- I had never seen such a beautiful sunset before I visited that beach.（在我去那个海滩之前，我从未见过如此美丽的日落。）
- By the time he arrived, the concert had already begun.（当他到达时，音乐会已经开始了。）
- She had done her homework before 10:00 last night. (她昨晚10点前就做完了家庭作业。)
- The rain had already stopped before 8:00 this morning. (今天早上8点前雨就停了。)
- He had left by the time I arrived. （我到的时候他已经离开了）
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| 主语 + had + been + 非动词 (基本不用) |
这里的"had"的作用就是来辅助“过去完成”这件事的，前面的课程中说过，过来帮忙的词叫“助动词”，所以"had"不再表达它原来的意思(拥有)，在这个时态里不需要翻译。过去完成时态常与其他过去时态构成复合时态或表达时间顺序上的先后关系。通常，它与 "before"， "after"， "by the time" 等时间状语连词一起使用。
| 过去完成时 |
现在完成时 |
| 过去的某个时间点或事件，表示在那个过去时间点之前已经发生或完成的动作或状态。 |
现在，表示从过去某个时间点开始一直延续到现在的动作或状态，或者强调与现在的关联。 |
- She had already left when I arrived.（她在我到达时已经离开了。）
- They had finished their work before the boss came.（老板来之前，他们已经完成了工作。）
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- I have already eaten breakfast today.（我今天已经吃过早饭了。）
- She has lived in this city for five years.（她在这个城市已经住了五年。）
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| 动作或状态在过去某个时间点之前就已经完成或发生了。 |
动作或状态可能在过去某个时间点开始，但它们与当前的情况仍然有关。 |
| 常与过去的时间状语连用，如 "before"、"after"、"by the time" 等。 |
常与涉及到现在的时间状语连用，如 "since"、"for"、"already"、"just"、"recently" 等。 |
时间状语
| by the end of…到......结束时 |
by the time sb. + 动词过去时 |
- by the end of last year 去年底指去年结束之前的某个时间点。
- by the end of last week 在上周以前
- by the end of last month… 在上个月以前
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- by the time he arrived... 在他到达的时候 The bus had already left by the time I got there.
- by the time I graduated… 到我毕业的时候 By the time he graduated,heI had already secured a job offer.
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| 陈述句 |
否定句 had + not |
疑问句 had 提前 |
| He had left by the time I arrived. |
He had not left by the time I arrived. |
Had he left by the time you arrived? |
