Complex sentence: "The Unnatural" is the nineteenth episode of the sixth season of the science fiction television series "The X-Files", which first aired on the Fox network on April 25,1999, and on July 4,1999 in the United Kingdom on Sky1.
Split into simpler sentences: The Unnatural is the nineteenth episode of the sixth season of the science fiction television series "The X-Files". The episode first aired on the Fox network on April 25,1999, and subsequently aired on July 4,1999 in the United Kingdom on Sky1.