What is perfect progressive tense?

There are three perfect progressive tenses: progressive past perfect for actions that were continually performed in the past but have not continued to the present; progressive present perfect for actions that have continued from the past into the present; and progressive future perfect for actions that are expected to continue at some time in the future but will come to a definite end. Example of progressive past perfect: He had been complaining constantly until he was given some ice cream. Example of progressive present perfect: He has been complaining constantly since early this afternoon. Example of progressive future perfect: I think he will have been complaining constantly from lunch time until supper time about how small his dessert at lunch was.