A man walking through a crowd on a city street.
The man is sitting on a roller coaster.
You wouldn't be walking through a crowd while sitting on a roller coaster.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & on(e1,x4) & n_street(x4) & of(x4,x5) & n_city(x5) & through(e1,x3) & n_crowd(x3) & Actor(e1,x2) & v_walk(e1) & (x1 = x2) & n_man(x1))
exists e1 x1 x2 x3.(n_man(x1) & on(e1,x2) & n_coaster(x2) & of(x2,x3) & n_roller(x3) & Actor(e1,x1) & v_sit(e1))