Children on rollerblades are playing hockey indoors.
Humans playing
Children is explaining species while children explain a specific age of the species.
exists e1 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_play(e1) & n_indoor(x3) & of(x3,x4) & n_hockey(x4) & on(x1,x2) & n_rollerblade(x2) & n_child(x1))
exists x1 x2.(n_playing(x1) & (x1 = x2) & ne_nam_humans(x2) & a_topic(x1))