A skier is coming down a hill.
A surfer on the ocean.
A skier skies on mountains which a surfer does not do.
exists e1 s1 x1 x2.(n_hill(x2) & Time(e1,x2) & a_down(s1) & Manner(e1,s1) & Actor(e1,x1) & v_come(e1) & n_skier(x1))
exists x1 x2.(n_ocean(x2) & a_topic(x1) & on(x1,x2) & n_surfer(x1))