CBS topped Tuesday with another big NCIS showing, while NBC's sitcoms slid to new lows.NCIS returned to 21.8 million viewers and a 3.7 in the adults 18-to-49 demographic, down two-tenths from its last new episode. NCIS: Los Angeles (17.2 million, 3.1) and Vegas (11.1 million, 1.9) were both up.Photos: 16 bad guys we root forA week after ... Read More > Other Links From TVGuide.com Dateline NBCNCISNCIS: Los AngelesHappy EndingsRaising HopeHart of DixieNew GirlBetty White's Off Their RockersEmily Owens, M.D.Go OnThe New NormalThe Mindy ProjectTake It AllThe Taste