CREATE TABLE table_name_79 (station VARCHAR2, country_of_origin VARCHAR2, frequency VARCHAR2)

Which station is from China and has a frequency of 684khz?
SELECT station FROM table_name_79 WHERE country_of_origin = "china" AND frequency = "684khz"
SELECT "station" FROM "table_name_79" WHERE "684khz" = "frequency" AND "china" = "country_of_origin"