user: Question: Who is the driver when the grid is 18?
Columns: ['Driver', 'Constructor', 'Laps', 'Time/Retired', 'Grid']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Alberto Ascari', 'Ferrari', '90', '2:53:35.8', '1']
SQL:

assistant: SELECT "Driver" FROM "Table" WHERE "Grid" = '18';