A youngster plays with a toy.
person walking on beach
One cannot be walking on a beach and playing with a toy simultaneously.
exists e1 x1 x2.(with(e1,x2) & n_toy(x2) & Actor(e1,x1) & v_play(e1) & n_youngster(x1))
exists x1 x2 x3.(a_topic(x1) & on(x1,x3) & n_beach(x3) & Time(x1,x2) & n_walking(x2) & n_person(x1))