A.heavy wall and intensive cooling B.heavy wall and no cooling C.thin wall and no cooling D.thin wall and intensive cooling
A.on both the external and internal top edges B.on both the external top and bottom edges C.on both the external and internal bottom edges D.on all the four edges
A.fuel valves;exhaust valve B.exhaust valves;inlet valve C.fuel valves;inlet valve D.exhaust valves;fuel valve