have/has been doing sth.
1.现在完成进行时
当后面接有一段时间的词时,或是加表示时间的词时,可以用现在完成时.如果这件事现在还在持续或还在做,则可用
现在完成进行时.
如:I have been skating for 4 hours.
I have finished my homework.
2.现在完成时的被动语态.
后接动词的过去分词.
如:The building has been built for 5 years.