Complex sentence: As the "Forrestal"-class "supercarriers" entered the fleet, the eight 27A conversions were designated CVS to replace the original unconverted ships; the latter began to leave active service in the late 1950s.
Split into simpler sentences: As the "Forrestal"-class "supercarriers" entered the fleet, the eight 27A conversions were designated CVS to replace the original unconverted ships. Unmodernized ships began to leave active service in the late 1950s.