They are playing with a soccer ball on the beach.
soccer players on a beach
They is more then one person and players are more then one player.  To play soccer you need a soccer ball.
exists e1 x1 x2 x3.(n_beach(x3) & with(e1,x1) & on(x1,x3) & n_ball(x1) & of(x1,x2) & n_soccer(x2) & Actor(e1,x1) & v_play(e1) & n_thing(x1))
exists x1 x2 x3.(a_topic(x1) & on(x1,x3) & n_beach(x3) & n_player(x1) & of(x1,x2) & n_soccer(x2))