Active: I had been cleaning the room.
Passive: The room had been being cleaned (by me.)
Active: I will have been doing my homework.
Passive: My homework will have been being done (by me).
Do these passive sentences give any sense? In other words, are past perfect progressive and future perfect progressive tense changeable to passive? Is there any rule which restricts the changing of a particular tense/tenses from active into passive?
Thanks, svartnik. That solves the problem.