Students are preparing for their band demonstration.
The students watched the science presentation.
preparing is not same as watched  band demonstration and science presentation are not the same
exists e1 x1 x2 x3.(for(e1,x2) & n_demonstration(x2) & of(x2,x3) & n_band(x3) & of(x2,x1) & n_thing(x1) & Actor(e1,x1) & v_prepare(e1) & n_student(x1))
exists e1 x1 x2 x3.(n_presentation(x2) & of(x2,x3) & n_science(x3) & n_student(x1) & Theme(e1,x2) & Actor(e1,x1) & v_watch(e1))