Kids on a ride at an amusement park.
The kids are on a roller coaster.
Just because kids are on an amusement park ride doesn't imply they are on a roller coaster.
exists x1 x2 x3 x4.(a_topic(x1) & on(x1,x2) & at(x2,x3) & n_park(x3) & of(x3,x4) & n_amusement(x4) & n_ride(x2) & n_kid(x1))
exists p1 x1.(n_kid(x1) & exists x2 x3.(on(x1,x2) & n_coaster(x2) & of(x2,x3) & n_roller(x3)))