Two children run on the beach.
The children is running
Two children run on the beach implies there is at least one children is running.
exists e1 x1 x2.(n_beach(x2) & on(e1,x2) & Actor(e1,x1) & v_run(e1) & n_child(x1) & card_eq_2(x1))
exists e1 x1.(n_child(x1) & Actor(e1,x1) & v_run(e1))