A person on a dirt bike is in the air.
The person is doing a trick for a crowd.
just because the bike is in the air does not mean he is doing a trick and there may or may not be a crowd there.
exists p1 x1 x2 x3 x4.(n_air(x4) & in(x1,x4) & on(x1,x2) & n_bike(x2) & of(x2,x3) & n_dirt(x3) & n_person(x1))
exists e1 x1 x2 x3.(n_person(x1) & Theme(e1,x2) & Actor(e1,x1) & v_do(e1) & for(x2,x3) & n_crowd(x3) & n_trick(x2))