Like their fellow Canadians Avril and Alanis, Tegan and Sara are a precocious punky pop act with a knack for writing brisk songs and vivisecting ex-lovers with a few tart phrases. On So Jealous, their third album, the twin sisters fully embrace new-wave synths and fuzzy rock rave-ups (''I Bet It Stung'' and ''Walking With a Ghost''), while their reedy voices trace the cork-screw path of relationships good and bad. But mostly bad.

