Kids playing in a tub of plastic balls.
The children sat at desks.
They cannot be playing in a tub and sitting at their desks at the same time.
exists e1 x1 x2 x3 x4 x5.(a_topic(x1) & in(e1,x3) & of(x3,x4) & n_ball(x4) & of(x4,x5) & n_plastic(x5) & n_tub(x3) & Actor(e1,x2) & v_play(e1) & (x1 = x2) & n_kid(x1))
exists e1 x1 x2.(n_child(x1) & at(e1,x2) & n_desk(x2) & Actor(e1,x1) & v_sit(e1))