A female student concentrates on her schoolwork.
A student is not focused on herself.
A student who concentrates is different from one not focused.
exists e1 s1 x1 x2.(on(e1,x2) & n_schoolwork(x2) & of(x2,x1) & n_female(x1) & Actor(e1,x1) & v_concentrate(e1) & n_student(x1) & a_female(s1) & Theme(s1,x1))
exists x1.(-exists e1.(on(e1,x1) & Theme(e1,x1) & v_focus(e1)) & n_female(x1) & n_student(x1))