Young boys playing flag football by a lake.
The boys are by a body of water.
if they are playing by a lake, they are by a body of water. a lake is a type of body of water.
exists e1 s1 x1 x2 x3 x4 x5.(a_topic(x1) & by(e1,x5) & n_lake(x5) & Theme(e1,x3) & Actor(e1,x2) & v_play(e1) & n_football(x3) & of(x3,x4) & n_flag(x4) & (x1 = x2) & n_boy(x1) & a_young(s1) & Theme(s1,x1))
exists p1 x1.(n_boy(x1) & exists x2 x3.(by(x1,x2) & of(x2,x3) & n_water(x3) & n_body(x2)))