user: Question: Name the round for engine of Ford Cosworth DFV 3.0 V8 with chassis fo 751
Columns: ['Entrant', 'Constructor', 'Chassis', 'Engine', 'Tyre', 'Driver', 'Rounds']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Marlboro Team McLaren', 'McLaren - Ford', 'M23', 'Ford Cosworth DFV 3.0 V8', 'G', 'Emerson Fittipaldi', 'All']
SQL:

assistant: SELECT "Rounds" FROM "Table" WHERE "Engine" = 'Ford Cosworth DFV 3.0 V8' AND "Chassis" = '751';