A person skis down a snowy hill.
A person is skiing.
skis and is skiing means the same thing.
exists e1 s1 s2 x1 x2.(a_down(s2) & Manner(e1,s2) & Theme(e1,x2) & Actor(e1,x1) & v_ski(e1) & n_hill(x2) & a_snowy(s1) & Theme(s1,x2) & n_person(x1))
exists p1 x1.(exists x2.((x1 = x2) & n_skiing(x2)) & n_person(x1))