A man is riding on a surfboard.
The surfer is in the ocean.
The man is riding on a surfboard, so the surfer is obviously in the ocean.
exists e1 x1 x2.(on(e1,x2) & n_surfboard(x2) & Actor(e1,x1) & v_ride(e1) & n_man(x1))
exists p1 x1 x2.(n_ocean(x2) & n_surfer(x1) & in(x1,x2))