New episodes of CBS's sitcom lineup returned to the air Monday following months of reruns due to the writers' strike, and ABC aired the season debut of its reality hit Dancing With The Stars, and although all of those shows received decent-to-good rati ngs, they were well off their comparable figures from a year ago. CBS declined 17 percent against last year's numbers for the comparable night. ABC was off 21 percent. For NBC and Fox, the plunge was far deeper, with NBC down 28 percent from last year a nd Fox, 32 percent. Reporting on the numbers, MediaWeek columnist Marc Berman asked, "Did the recent writers' strike cause permanent damage?" Berman pointed out that while ABC's Dancing With the Stars premiere averaged a solid 13.4 rating an d a 21 share, a year ago it opened with a 15.1/22.