user: Question: What shows for round when the race was Int. ADAC Preis von Zweibrücken?
Columns: ['Round', 'Race', 'Circuit', 'Date', 'Event', 'Winning driver']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Int. ADAC-Preis Hockenheim', 'Hockenheimring', '19 April', 'Sprint Race', 'Uwe Alzen Manuel Reuter']
SQL:

assistant: SELECT "Round" FROM "Table" WHERE "Race" = 'Int. ADAC Preis von Zweibrücken';