先看has been doing：It has been raining for 3 days.雨一直下了3天都没停（到说话的时点为止雨还在下）区别于，It has rained for 3 days.已经下了3天的雨（说话时，雨已经停了。）现在看had been doing，很明显，had been doing在时态上发生得比has been doing 早，那么再以上面的例句为例，Last friday, I said that it had been raining for a long time. 主句时态势过去时，而从句发生得比主句早，所以应该是过去完成时，但我要表达的是，雨连续下了很久但到我说话的还没有停，所以用过去完成进行时。...
你随便看一个理解吧方法一:过去完成进行时,had been doing,语法书上写的,语法功底好的话,一眼就能看出来.must have been doing must表示很肯定地猜测,must是情态动词,跟时态没多大的关系,最多就随着时态变成过去式之类的.方法二:首先看到had been,就是have +过去分词,就是完成时,hav...
1.过去完成进行时：had been doing例：The old clock had been being taken apart of and fixed up again for several times by my 10-year old son before I came back home.（我回到家之前，我10岁大的儿子已经把这个...
