过去将来完成时表示从过去观点看将来某时某动作已完成。 在英语时态中，“时“指动作发生的时间，”态“指动作的样子和状态。
时态用法
如：
1:I thought Sophia would have told you something;
我想索菲娅会告诉你一些事情。
2:He knew by the time he arrived she would have gone home;
在他到时他才知道她已经回家了。
3:The day was drawing near when we would have completed the reservoir;
我们建成水库的日子不远了。
4:He said he would have done with my camera by the end of next month;
他说到下月底就不用我的照相机了。
5:I guessed that Mother would have made some sandwiches by the time we got back.
若表示与过去事实相反的
虚拟语气，此时
条件从句的谓语用
过去完成时(had+
过去分词)，而
主句谓语则通常用过去将来完成时（would+have+过去分词），当然，主句谓语也可根据情况使用“should (could, might)+have+过去分词”。
如：
1:If I’d left sooner, I'd have been on time;
要是我早点动身，我就准时到了。(但我动身太迟了)
2:If we had found him earlier we could have saved his life;
要是我们当时早点找到他的话，我们就可以救活他。(可惜我们找到他太晚了)
3:If I had known that you were coming I would have met you at the air-port;
要是我早知道你要来的话，我就会在机场接你了。
4:If he had lived, some day Michael would have done something important;
假定麦克尔当时在世的话，他本可做出了不起的事。
5:If I had known how he felt, I would never have let him adopt those children;
我要是知道他的想法，我是决不会让他领养那些孩子的。
6:He would have forgotten the boy’s
birthday if you hadn’t reminded him;
要不是你提醒他，他会忘记这男孩的生日的。
7:Our lives would have been
greatly impoverished if we had not known our dear friend;
若不是得识我们这位好朋友，我们的生活一定十分不妙。
“would + have +
过去分词”的情态用法：
would 后接完成式除用于构成过去将来完成时外，它还有其
情态动词用法的一面。
如：
1:Only somebody with a small mind would have refused to help;
只有心胸狭窄的人才不肯帮助别人。（表推测）
2:Few men would have bared their soul to a woman as he had;
很少有男人能像他一样对一个女人敞开心扉。（表怀疑）
3:I’m surprised you didn’t like the film. I would have thought it was just your kind of thing;
你不喜欢这部电影，这让我感到奇怪。我本来还觉得正对你的路呢。（表过去的想法）
4:My father would have driven me to Cornwall, but we decided it would be quicker by train;
父亲原本要开车送我去
康沃尔，但我们还是觉得
坐火车更快。（表过去的想法）
5:The scar added interest to a face that otherwise would have appeared too bland.
这处伤疤为本显得平淡无奇的脸增添了些吸引力。（表示未曾发生的情况）