A person waving is hanging off a zip line.
A person is on a zip line.
The method of being on a zip line is hanging off.
exists p1 x1.(a_topic(x1) & exists e1 s1 x2 x3 x4.(a_off(s1) & Manner(e1,s1) & Theme(e1,x3) & Actor(e1,x2) & v_hang(e1) & n_line(x3) & of(x3,x4) & n_zip(x4) & n_waving(x2)) & that(x1,p1) & n_person(x1))
exists p1 x1.(exists x2 x3.(on(x1,x2) & n_line(x2) & of(x2,x3) & n_zip(x3)) & n_person(x1))