CREATE TABLE table_28044 ("Series no." FLOAT, "No. in season" FLOAT, "Title" CLOB, "Written by" CLOB, "Directed by" CLOB, "Original air date" CLOB, "U.S. viewers  ( millions ) " CLOB)

Who wrote the episode where the original air date is july20,2007?
SELECT "Written by" FROM table_28044 WHERE "Original air date" = 'July20,2007'
SELECT "Written by" FROM "table_28044" WHERE "Original air date" = 'July20,2007'