CREATE TABLE table_name_18 (release_date VARCHAR2, release_format VARCHAR2, country VARCHAR2)

What is the release date for the standard cd release format in north america?
SELECT release_date FROM table_name_18 WHERE release_format = "standard cd" AND country = "north america"
SELECT "release_date" FROM "table_name_18" WHERE "country" = "north america" AND "release_format" = "standard cd"