Two motorcycle racers are driving on a race course.
There are two racers on a race course.
Motorcycle racers and just racers may be different type of vehicle, and the racers could be walking on the race course and not driving.
exists e1 x1 x2 x3 x4.(on(e1,x3) & n_course(x3) & of(x3,x4) & n_race(x4) & Actor(e1,x1) & v_drive(e1) & n_racer(x1) & of(x1,x2) & n_motorcycle(x2) & card_eq_2(x1))
exists p1 x1 x2 x3 x4.((x1 = x2) & on(x2,x3) & n_course(x3) & of(x3,x4) & n_race(x4) & n_racer(x2) & card_eq_2(x2))