Question: Give me a list of cities whose temperature in Feb is higher than that in Jun or cities that were once host cities?
SQL: SELECT T1.city FROM city AS T1 JOIN temperature AS T2 ON T1.city_id  =  T2.city_id WHERE T2.Feb  >  T2.Jun UNION SELECT T3.city FROM city AS T3 JOIN hosting_city AS T4 ON T3.city_id  =  T4.host_city