The boy is playing in the sand.
The boy is going to build sand castles.
Not all boys playing in the sand is going to build sand castles.
exists e1 x1 x2.(n_sand(x2) & n_boy(x1) & in(e1,x2) & Actor(e1,x1) & v_play(e1))
exists e1 p1 x1.(n_boy(x1) & Topic(e1,p1) & Actor(e1,x1) & v_go(e1) & exists e2 x2 x3.(Theme(e2,x2) & Actor(e2,x1) & v_build(e2) & n_castle(x2) & of(x2,x3) & n_sand(x3)))