We can use the past perfect continuous to talk about events which started before a time in the past and which finished, but where the effects or results were still important at a point in the past:
以上讲解源于《剑桥英语字典-语法栏》
例句1. It had been raining and the ground was still wet.
假如改用目前完成进行时
例句2. It has been raining and the ground is still wet
按目前完成进行时的概念，其要么依旧在发生中，要么在不久前已经停止。所以在上句中，大家了解雨下了很长时间，但刚停了，只不过地依旧是湿的。
目前回到例句1，大家假设说话人表示the ground was still wet是过去的时间点A，雨停的时间点是B，那样依据之前剑桥的解释，则大家没办法了解B点到A点的时间距离，或许1分句，或许1整天也依旧可以。
求证一下，是否我这种理解是正确的。
剑桥词典的这个讲解并不严谨。由于这个讲解没办法区别过去完成时和过去完成进行时有什么区别。比如：
例句1. It had been raining and the ground was still wet.
例句2. It had rained and the groundwas still wet.
学习时态的使用方法，还是应该好好看一本书法书，词典的篇幅有限，很难说明问题。
完成体和完成进行体都可以表示过去事件对随后某个时间的影响或产生的结果。但二者的侧重点不同。完成体的结果是因为事件的结束而产生的，完成进行体是因为事件的持续而产生的。比如：
He had cleaned the room and so the room was nice and tidy.
He had been cleaning the room and so he was very tired.
房间的整洁是打扫完成产生的结果。某人疲倦是打扫动作持续发生产生的结果。剑桥词典的讲解和例句都没可以反映这一点。据此学习过去完成时使用方法，会被误导的。
