过去将来完成时 (Future Perfect in the Past)

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

↑ ------------------------ ↑

从过去看 --------在过去将来某时间点之前要完成的动作

这种时态用于描述从过去某一时间点来看，在将来某一时刻之前要完成的动作。

语法形式

过去将来完成时的构成是：主语 + would have + 过去分词

• 肯定句：主语 + would have + 过去分词

  • I would have finished.
  • She would have graduated.

• 否定句：主语 + would not have + 过去分词

  • I would not (wouldn't) have finished.
  • She would not (wouldn't) have graduated.

• 疑问句：Would + 主语 + have + 过去分词？

  • Would you have finished?
  • Would she have graduated?

应用场景

1. 表示过去预期的将来完成的动作

用于描述在过去某一时刻，预期在将来某个时间点之前要完成的动作。

示例：

• He said he would have finished the work by Friday. (他说他会在星期五之前完成工作。)
• I knew she would have left before I arrived. (我知道在我到达之前她就会离开。)

2. 间接引语中的将来完成时

在间接引语中，将来完成时变成过去将来完成时。

示例：

• Direct: "I will have completed the project by next week." (我下周之前会完成这个项目。)
• Indirect: She said she would have completed the project by the following week. (她说她会在下周之前完成这个项目。)

3. 表示未实现的过去假设

用于表示过去某个未能实现的假设情况。

示例：

• I would have finished the work if you had helped me. (如果你帮我的话，我就能完成这项工作了。)
• She would have graduated by now if she hadn't quit school. (如果她没有退学的话，她现在已经毕业了。)

与其他时态的对比

过去将来完成时 vs 将来完成时

过去将来完成时是从过去的视角看将来的完成动作，而将来完成时是从现在的视角看将来的完成动作。

示例：

• I will have finished the work by tomorrow. (将来完成时 - 从现在看)
• He said he would have finished the work by the next day. (过去将来完成时 - 从过去看)

过去将来完成时 vs 过去完成时

过去将来完成时表示在过去某一时刻之后要完成的动作，而过去完成时表示在过去某一时刻之前已经完成的动作。

示例：

• I had finished the work before he arrived. (过去完成时 - 过去的完成)
• I knew I would have finished the work before he arrived. (过去将来完成时 - 过去对将来的预期)

常见用法和例句

1. 在从句中的使用

常用于宾语从句、时间从句等：

• I thought you would have arrived by then.
• She wondered if he would have received her letter.

2. 表示预期的完成

用于表达过去对将来完成的预期：

• We expected that they would have solved the problem by the meeting.
• The teacher said we would have learned all the grammar by the end of the term.

3. 虚拟语气中的使用

用于表达与过去事实相反的假设：

• If I had studied harder, I would have passed the exam.
• She would have caught the train if she had left earlier.

注意事项

1. 过去将来完成时通常需要一个明确的时间参照点：

   • ✔️ He said he would have finished by Monday.
   • ❌ He said he would have finished. (缺少时间参照点)

2. 在时间状语从句中，要用现在完成时而不是过去将来完成时：

   • When I have finished (不是 would have finished), I will call you.
   • After she has graduated (不是 would have graduated), she plans to travel.

3. 过去将来完成时常与以下时间表达一起使用：

   • by then
   • by that time
   • by the end of...
   • before...
   • when...