Passengers boarding a train.
The people are on the train
people are on the train refer to passengers.
exists e1 x1 x2.(ne_nam_passengers(x1) & Theme(e1,x2) & Actor(e1,x1) & v_board(e1) & n_train(x2))
exists p1 x1 x2.(n_train(x2) & n_people(x1) & on(x1,x2))