Table: cities_underworld_episodes_2
Columns: production_no
episode_no
original_airdate
episode_title
host

Question: What is the title of the episode that originally aired on March 31, 2008?
SQL: SELECT "episode_title" FROM cities_underworld_episodes_2 WHERE "original_airdate" = 'march 31, 2008'

Question: What is the episode number of the episode that originally aired on February 4, 2008?
SQL: SELECT "episode_no" FROM cities_underworld_episodes_2 WHERE "original_airdate" = 'february 4, 2008'