A small boy is riding a water slide
A child is at a waterpark.
waterpark is  a kind of  a waterslide.
exists e1 s1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_slide(x2) & of(x2,x3) & n_water(x3) & n_boy(x1) & a_small(s1) & Theme(s1,x1))
exists p1 x1.(exists x2.(at(x1,x2) & n_waterpark(x2)) & n_child(x1))