Two boys are playing ping-pong.
Two brothers play ping pong on a green table.
two boys doesn't mean they are brother. Also ping-pong can be played on more than a green table
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_ping-pong(x2) & n_boy(x1) & card_eq_2(x1))
exists e2 e1 s1 x1 x2 x3.(Theme(e2,x2) & Actor(e2,x1) & v_play(e2) & on(x2,x3) & n_table(x3) & a_green(s1) & Theme(s1,x3) & n_pong(x2) & Actor(e1,x2) & v_ping(e1) & n_brother(x1) & card_eq_2(x1))