Singular	Plural
I have been walking	we have been walking
you have been walking	you have been walking
he/she/it has been walking	they have been walking

Singular	Plural
I have been sleeping	we have been sleeping
you have been sleeping	you have been sleeping
he/she/it has been sleeping	they have been sleeping

Singular	Plural
There is no present perfect progressive for the "to be" verb. "Have been being" is expressed simply as "have been": "We have been being successful in the past."