THE MIDDLE - "Twenty Years" - As their 20th anniversary approaches, Frankie begins to think that Mike may be tiring of her company and is purposely trying to avoid her. Meanwhile, Sue frantically tries to coax Axl and Brick into helping her set up an anniversary party for their parents, and Brick falls into a non-responsive state when Axl tells him the ending of a book he's been waiting years to read, on "The Middle," WEDNESDAY, DECEMBER 12 (8:00-8:30 p.m., ET) on the ABC Television Network. (ABC/MICHAEL ANSELL) PATRICIA HEATON