Table: air_routes
Columns: rank
city_1
city_2
2012_passengers_in_millions
2011_passengers_in_millions
distance

Question: How many passengers (in millions) flew from Seoul in 2012?
SQL: SELECT "2012_passengers_in_millions" FROM air_routes WHERE "city_1" = 'Seoul'

Question: What the is the first city listed on the route that had 6.6+ passengers in 2011 and a distance of 1075km?
SQL: SELECT "city_1" FROM air_routes WHERE "2011_passengers_in_millions" = '6.6+' AND "distance" = '1075km'

Question: How many passengers (in millions) flew through along the route that is 1075km long in 2012?
SQL: SELECT "2012_passengers_in_millions" FROM air_routes WHERE "distance" = '1075km'

Question: How many passengers (in millions) in 2011 flew through along the route that had 6.640 million passengers in 2012?
SQL: SELECT "2011_passengers_in_millions" FROM air_routes WHERE "2012_passengers_in_millions" = '6.640'

Question: Which city is listed first when Okinawa is listed as the second city?
SQL: SELECT "city_1" FROM air_routes WHERE "city_2" = 'Okinawa'

Question: In 2011, which city is listed first along the route that had 7.6+ million passengers?
SQL: SELECT "city_1" FROM air_routes WHERE "2011_passengers_in_millions" = '7.6+'