A teacher is giving a lecture.
The teacher is sitting at the back of the room.
If the teacher is giving the lecture, it is more likely the teacher would be standing at the front of the room.
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_room(x3) & n_back(x2) & n_teacher(x1) & at(e1,x2) & of(x2,x3) & Actor(e1,x1) & v_sit(e1))