A child rides an orange boogie board in the waves while an adult looks on from the water.
The child is building a sandcastle.
A child is a general statement while The child is allot more specific.
exists e1 p1 x1 x2 x3 x4 x5 x7.(n_water(x7) & n_wave(x5) & exists e2 x6.(r_on(e2) & from(e2,x7) & Actor(e2,x6) & v_look(e2) & n_adult(x6)) & while(e1,p1) & in(e1,x5) & Theme(e1,x2) & Actor(e1,x1) & v_ride(e1) & n_board(x2) & of(x2,x4) & n_boogie(x4) & of(x2,x3) & n_orange(x3) & n_child(x1))
exists e1 x1 x2.(n_child(x1) & Theme(e1,x2) & Actor(e1,x1) & v_build(e1) & n_sandcastle(x2))