A teacher is giving a lecture.
The teacher is looking at the powerpoint presentation.
Not all lectures are given by powerpoint presentations.
exists e1 x1 x2.(Theme(e1,x2) & Actor(e1,x1) & v_give(e1) & n_lecture(x2) & n_teacher(x1))
exists e1 x1 x2 x3.(n_presentation(x2) & of(x2,x3) & n_powerpoint(x3) & n_teacher(x1) & at(e1,x2) & Actor(e1,x1) & v_look(e1))