Two people go dirt bike racing.
A couple people ride rollerblades in the dirt.
Either the people are using dirt bikes or roller blades.
exists e1 x1 x2 x3 x4.(Theme(e1,x2) & Actor(e1,x1) & v_go(e1) & n_racing(x2) & of(x2,x4) & n_bike(x4) & of(x2,x3) & n_dirt(x3) & n_people(x1) & card_eq_2(x1))
exists e1 x1 x2 x3 x4.(n_dirt(x4) & in(e1,x4) & Theme(e1,x3) & Actor(e1,x1) & v_ride(e1) & n_rollerblade(x3) & n_people(x1) & of(x1,x2) & n_couple(x2))