People are waiting in line for a train.
People wait in line for a train.
Waiting in line and wait in line mean the same thing.
exists e1 x1 x2 x3.(for(e1,x3) & n_train(x3) & in(e1,x2) & n_line(x2) & Actor(e1,x1) & v_wait(e1) & n_people(x1))
exists e1 x1 x2 x3.(in(e1,x3) & n_line(x3) & for(e1,x2) & n_train(x2) & Actor(e1,x1) & v_wait(e1) & n_people(x1))