a woman staring off while on a bus.
A woman looks outside while riding the bus.
staring off while on a bus is inferred as  looks outside while riding the bus.
exists e1 s1 x1 x2 x3.(a_topic(x1) & on(e1,x3) & n_bus(x3) & r_while(e1) & a_off(s1) & Manner(e1,s1) & Actor(e1,x2) & v_stare(e1) & (x1 = x2) & n_woman(x1))
exists e2 e1 s1 x1 x2.(n_bus(x2) & while(e1,e2) & Theme(e2,x2) & Actor(e2,x1) & v_ride(e2) & a_outside(s1) & Manner(e1,s1) & Actor(e1,x1) & v_look(e1) & n_woman(x1))