People sitting on a bus at night.
There is a group of people riding a bus down a highway.
The bus may not be moving, so they may not be riding, and even if they are, it isn't necessarily down a highway.
exists e1 x1 x2 x3 x4.(a_topic(x1) & at(e1,x4) & n_night(x4) & on(e1,x3) & n_bus(x3) & Actor(e1,x2) & v_sit(e1) & (x1 = x2) & n_people(x1))
exists p1 x1 e1 x2 x3 x4 x5 x6.((x1 = x2) & of(x2,x3) & down(e1,x6) & n_highway(x6) & Theme(e1,x5) & Actor(e1,x4) & v_ride(e1) & n_bus(x5) & (x3 = x4) & n_people(x3) & n_group(x2))