What is the use of perfect continuous tenses?
We use the present perfect continuous tense to talk about an action that started in the past and is continuing in the present.
I have been listening to music since morning.
Past perfect continuous tense shows that the action was going on continuously, and did not complete in the past.
I had been working on this project.
The future perfect continuous tense shows an action or event that will be taking place at some moment in the future, before another action or event.
He will have been dancing for three hours before the recital ends.