Complex sentence: Supermax (TV channel) was a czech chanel that featured mostly animated series for teens and pre-teens.It has been on the air since 2004 and was replaced by the children channel Minimax (TV channel).
Split into simpler sentences: Supermax (TV channel) was a Czech channel that featured mostly animated television programs for teens and pre-teens. It went on has been on the air since 2004 and was replaced by the children channel Minimax (TV channel).