Four females stand on the tip of their toes while practicing ballet in front of a black backdrop.
The females know how to dance ballet.
The females know how to dance ballet if they are able to stand on the tip of their toes while practicing ballet.
exists e1 e2 s1 x1 x2 x3 x4 x5 x6.(n_toe(x3) & of(x3,x2) & n_thing(x2) & n_tip(x2) & while(e1,e2) & in(e2,x5) & of(x5,x6) & n_backdrop(x6) & a_black(s1) & Theme(s1,x6) & n_front(x5) & Theme(e2,x4) & Actor(e2,x1) & v_practice(e2) & n_ballet(x4) & on(e1,x2) & of(x2,x3) & Actor(e1,x1) & v_stand(e1) & n_female(x1) & card_eq_4(x1))
exists e1 x1 x2.(n_female(x1) & Topic(e1,x2) & Actor(e1,x1) & v_know(e1) & n_manner(x2) & exists e2 x3 x4.(Theme(e2,x4) & Actor(e2,x3) & v_dance(e2) & n_ballet(x4)))