A person in protective equipment riding a dirt bike.
There is a person on a dirt bike.
A person who is riding a dirt bike is on a dirt bike.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & Theme(e1,x4) & Actor(e1,x3) & v_ride(e1) & n_bike(x4) & of(x4,x5) & n_dirt(x5) & (x1 = x3) & in(x1,x2) & n_equipment(x2) & a_protective(s1) & Theme(s1,x2) & n_person(x1))
exists p1 x1 x2 x3 x4.((x1 = x2) & on(x2,x3) & n_bike(x3) & of(x3,x4) & n_dirt(x4) & n_person(x2))