user: Question: Which line was green?
Columns: ['Line', 'Colour', 'Route', 'Length', 'Stations']
Types: ['text', 'text', 'text', 'text', 'real']
Sample row: ['U 1', 'red', 'Reumannplatz – Leopoldau', '14.6km (9.1mi)', 19.0]
SQL:

assistant: SELECT "Line" FROM "Table" WHERE "Colour" = 'green';