Hi, when to use seen??

Every Past participle (V3).. is used in the perfect tenses (active voice), as well as in their passive voice too. present perfect : He has seen a movie just now. (active) A movie has been seen by him just now. (passive) past perfect : he had seen the accident before he talked to me. (active) the accident had been seen by him before he talked to me. (passive) Future perfect : I will have seen the Taj Mahal by this time tomorrow. (active) The Taj Mahal will have been seen by me by this time tomorrow. (passive)