请问这句英文为什么要用been,是属什么语法

问题描述:

请问这句英文为什么要用been,是属什么语法
He's been in the doldrums ever since she
left him.
自从她离开他以来,他一直很消沉.

现在完成时,它的结构是:助动词have /has +动词的过去分词,主语是HE,故用has ( he's been = has been ),be的过去分词是:beenhe's 不是 he is 的缩写吗?不是,因为he's been = He has been ( 现在完成时的结构)
区别: He's a student.= He is a student.