A girl in a black shirt is watching a chemical reaction.
A girl is in her chemistry class
A girl watching a chemical reaction may or may not be in her chemistry class.
exists e1 s1 x1 x2 x3 x4.(Theme(e1,x3) & Actor(e1,x1) & v_watch(e1) & n_reaction(x3) & of(x3,x4) & n_chemical(x4) & in(x1,x2) & n_shirt(x2) & a_black(s1) & Theme(s1,x2) & n_girl(x1))
exists p1 x1 x2 x3.(in(x1,x2) & n_class(x2) & of(x2,x3) & n_chemistry(x3) & of(x2,x1) & n_female(x1) & n_girl(x1))