Question: who are the writers of the episode that had 3.07 millions of North American spectators?
SQL: SELECT "Written by" FROM "1-21979779-1" WHERE "U.S. viewers (million)" = '3.07';

Question: what is the biggest series episode number whose production code is 2T7211?
SQL: SELECT MAX("No.") FROM "1-21979779-1" WHERE "Production code" = '2T7211';

Question: what is the smallest series episode number whose production code is 2T7211?
SQL: SELECT MIN("No.") FROM "1-21979779-1" WHERE "Production code" = '2T7211';

Question: when was the premiere of the episode where the amount of North American spectators was 1.76 millions?
SQL: SELECT "Original air date" FROM "1-21979779-1" WHERE "U.S. viewers (million)" = '1.76';