The man is on a ski boat in the water.
Man trains for ski boat race
The man is on a ski boat in the water but not for trains for race.
exists p1 x1 x4.(n_water(x4) & n_man(x1) & exists x2 x3.(on(x1,x2) & in(x2,x4) & n_boat(x2) & of(x2,x3) & n_ski(x3)))
exists x1 x2 x3 x4 x5.(a_topic(x1) & for(x1,x3) & n_race(x3) & of(x3,x5) & n_boat(x5) & of(x3,x4) & n_ski(x4) & n_train(x1) & of(x1,x2) & n_man(x2))