had been done是什么时态

过去将来完成进行时：(would have been doing)

表示动作从过去某一时间开始一直延续到过去将来某一时间，期间一直有规律在进行、不曾间断，并且有可能继续延续下去。

例：They said that by the end of the following month, the project would have been being worked for 3 years.

他们说到第二个月底为止，这项工程就已经不停地进行了3年了。

将来完成时(will have done)

①表示一个动作到将来某个时间为止已经完成，强调对将来那个时间产生的影响。

例：Pick me up at 8 o'clock,I will have had breakfast by then.

早上8点钟你来接我,到时我已经吃完早饭了.

②表示一个动作延续到将来某个时间，并且有可能继续延续下去。

例：The conference will have lasted a full week by the time it ends.

会议从开始到结束将持续整整一个星期。

将来完成进行时：(will have been doing)

表示一个动作延续到将来某个时间，期间一直有规律在进行、不曾间断，并且有可能继续延续下去。

例：By the end of next month, the project will have been being worked for 3 years.

到下个月底为止，这项工程就已经不停地进行了3年了。