Two people on a motorcycle.
A couple is sitting on a motorcycle.
Both subjects are on a motorcycle
exists x1 x2.(a_topic(x1) & on(x1,x2) & n_motorcycle(x2) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2.(on(e1,x2) & n_motorcycle(x2) & Actor(e1,x1) & v_sit(e1) & n_couple(x1))