A boy playing in a lake
A boy fishing.
The boy cannot be playing and fishing at the same time.
exists x1 x2 x3.(a_topic(x1) & in(x1,x3) & n_lake(x3) & n_playing(x1) & of(x1,x2) & n_boy(x2))
exists x1 x2.(a_topic(x1) & n_fishing(x1) & of(x1,x2) & n_boy(x2))