person skiing off a mountain
A person skiis down a snowy mountain
If a person is skiing off a mountain then he skiis down a snowy mountain.
exists x1 x2 x3 x4.(a_topic(x3) & Time(x3,x4) & n_skiing(x4) & n_person(x3) & off(x2,x1) & n_person(x2) & n_mountain(x1))
exists e1 s1 s2 x1 x2.(a_down(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_skii(e1) & n_mountain(x2) & a_snowy(s1) & Theme(s1,x2) & n_person(x1))