user: Question: Name the circuit for round 18
Columns: ['Round', 'Date', 'Grand Prix', 'Circuit', '125cc winner', '250cc winner', 'MotoGP winner', 'Report']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '9 March', 'Qatar Grand Prix ‡', 'Losail', 'Sergio Gadea', 'Mattia Pasini', 'Casey Stoner', 'Report']
SQL:

assistant: SELECT "Circuit" FROM "Table" WHERE "Round" = 18.0;