students study outside on the grass
students playing
One cannot  study while playing.
exists e1 s1 x1 x2.(n_grass(x2) & on(e1,x2) & a_outside(s1) & Manner(e1,s1) & Actor(e1,x1) & v_study(e1) & n_student(x1))
exists e1 x1 x2.(a_topic(x1) & Actor(e1,x2) & v_play(e1) & (x1 = x2) & n_student(x1))