Question: who directed the production code 2T5710?
SQL: SELECT "Directed by" FROM "1-21726793-1" WHERE "Production code" = '2T5710';

Question: what is the total number o production code where us viewers is 2.76?
SQL: SELECT COUNT("Production code") FROM "1-21726793-1" WHERE "U.S. viewers (million)" = '2.76';

Question: who wrote the no 2?
SQL: SELECT "Written by" FROM "1-21726793-1" WHERE "No." = 2.0;