user: Question: When did Yugoslavia play a Friendly game in Belgrade?
Columns: ['Date', 'City', 'Opponent', 'Results¹', 'Type of game']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['February 13', 'Frankfurt , Germany', 'Spain', '1:0', 'WC 1974 qualifying']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "City" = 'Belgrade' AND "Type of game" = 'Friendly';