boy doing tricks on a skateboard
The boy cannot use a skateboard.
If someone cannot use a skateboard he can't be doing tricks.
exists e1 x1 x2 x3 x4.(a_topic(x1) & on(e1,x4) & n_skateboard(x4) & Theme(e1,x3) & Actor(e1,x2) & v_do(e1) & n_trick(x3) & (x1 = x2) & n_boy(x1))
exists x1.(n_boy(x1) & -exists e1 p1.(exists e2 x2.(Theme(e2,x2) & Actor(e2,x1) & v_use(e2) & n_skateboard(x2)) & Topic(e1,p1) & Actor(e1,x1) & v_can(e1)))