A man is attempting a skateboard trick.
A man is on a skateboard.
A man can only do a skateboard trick if he is on a skateboard.
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_attempt(e1) & n_trick(x2) & of(x2,x3) & n_skateboard(x3) & n_man(x1))
exists p1 x1.(exists x2.(on(x1,x2) & n_skateboard(x2)) & n_man(x1))