African Americans sitting on chairs in a classroom.
The chairs are blue.
Not all chairs are blue.
exists e1 s1 s2 x1 x2 x3.(ne_nam_americans(s1) & a_african(s2) & Theme(s2,s1) & a_topic(s1) & in(e1,x3) & n_classroom(x3) & on(e1,x2) & n_chair(x2) & Actor(e1,x1) & v_sit(e1) & (s1 = x1))
exists s1 x1.(n_chair(x1) & Theme(s1,x1) & a_blue(s1))