Complex sentence: The first appearance of a holodeck came in the "Star Trek" animated series (1974): during the episode "The Practical Joker", Dr McCoy, Sulu and Uhura are trapped inside it by the ship's computer.
Split into simpler sentences: The first appearance of a holodeck came in the "Star Trek" animated series (1974). During the episode "The Practical Joker", Dr McCoy, Sulu and Uhura are trapped inside it by the ship's computer.