City workers are doing maintenance on a train track.
workers perform maintainance on a train track
" Doing maintenance " is the same thing as to " perform maintenance "
exists e1 x1 x2 x3 x4 x5.(on(e1,x4) & n_track(x4) & of(x4,x5) & n_train(x5) & Theme(e1,x3) & Actor(e1,x1) & v_do(e1) & n_maintenance(x3) & n_worker(x1) & (x1 = x2) & ne_geo_city(x2))
exists e1 x1 x2 x3 x4.(on(e1,x3) & n_track(x3) & of(x3,x4) & n_train(x4) & Theme(e1,x2) & Actor(e1,x1) & v_perform(e1) & n_maintainance(x2) & n_worker(x1))