A repairman is working on a train.
The train is broken down and the passengers are waiting.
Just because a repairman is working on a train does not mean it is broken down. It is unknown if the passengers are waiting.
exists e1 x1 x2.(on(e1,x2) & n_train(x2) & Actor(e1,x1) & v_work(e1) & n_repairman(x1))
exists e2 e1 p1 x1 x2.(n_passenger(x2) & n_train(x1) & Actor(e2,x2) & v_wait(e2) & exists s1.(Theme(s1,x1) & a_down(s1)) & Recipient(e1,p1) & Topic(e1,x1) & v_break(e1))