A man works on the wheel of a train.
Someone is working on a mechanical system here.
A man of someone work on the wheel of a train a mechanical system
exists e1 x1 x2 x3.(n_wheel(x2) & on(e1,x2) & of(x2,x3) & n_train(x3) & Actor(e1,x1) & v_work(e1) & n_man(x1))
exists e1 s1 s2 x1 x2.(a_here(s2) & Manner(e1,s2) & on(e1,x2) & n_system(x2) & a_mechanical(s1) & Theme(s1,x2) & Actor(e1,x1) & v_work(e1) & n_person(x1))