Children stand and wait for the train.
Some children are waiting for a train.
If children wait for the train then children are waiting.
exists e1 s1 x1 x2 x3 x4.(n_train(x4) & a_topic(s1) & subset_of(x3,s1) & for(x3,x4) & n_wait(x3) & subset_of(x1,s1) & Actor(e1,x2) & v_stand(e1) & (x1 = x2) & n_child(x1))
exists e1 x1 x2.(for(e1,x2) & n_train(x2) & Actor(e1,x1) & v_wait(e1) & n_child(x1))