An aspirin added to the water would preserve the flowers.
Adding aspirin to the water could kill the plant.
Instead of preserving the flowers the aspirin is said to kill the flowers.
exists e2 e1 x1 x2 x3 x4.(n_flower(x4) & n_water(x2) & to(e1,x2) & Theme(e2,x4) & Actor(e2,x3) & v_preserve(e2) & (x2 = x3) & Actor(e1,x1) & v_add(e1) & n_aspirin(x1))
exists e1 e2 p1 x1 x2 x3 x4.(n_plant(x4) & n_water(x3) & exists e3.(Theme(e3,x4) & Actor(e3,e1) & v_kill(e3)) & Topic(e2,p1) & Actor(e2,e1) & v_could(e2) & to(e1,x3) & Theme(e1,x2) & Actor(e1,x1) & v_add(e1) & n_aspirin(x2) & n_thing(x1))