Two people in racing clothes and helmets are riding motorcycles.
Two people lead the motorcycle race.
Two people in racing clothes and helmets are riding motorcycles does not imply they  lead the motorcycle race
exists e1 e2 x1 x2 x3 x4 x5 x6.(Theme(e2,x6) & Actor(e2,x1) & v_ride(e2) & n_motorcycle(x6) & Theme(e1,x3) & Actor(e1,x2) & v_race(e1) & subset_of(x5,x3) & n_helmet(x5) & subset_of(x4,x3) & n_clothes(x4) & (x1 = x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2 x3.(n_race(x2) & of(x2,x3) & n_motorcycle(x3) & Theme(e1,x2) & Actor(e1,x1) & v_lead(e1) & n_people(x1) & card_eq_2(x1))