Whitney 8 p.m., Channel 7

NBC can be a little stubborn about holding onto its sitcoms, for good (“Parks and Recreation”) and for ill (“The Office,” season 9). Despite fairly crummy ratings, the network renewed “Whitney,” and it returns for season 2 on Wednesday night. It’s a mediocre half-hour, with lots of weak one-liners built on cliched gender humor about couples. Whitney Cummings and Chris D’Elia have great chemistry; too bad the writing doesn’t serve them better.