Person riding dirt bike on track while others stand by track
People watch someone riding a dirt bike.
others refer to people.
(x)
exists e2 e1 x1 x2 x3 x4 x5.(Theme(e2,x2) & Actor(e2,x1) & v_watch(e2) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_bike(x4) & of(x4,x5) & n_dirt(x5) & (x2 = x3) & n_person(x2) & n_people(x1))