An aspirin added to the water would preserve the flowers.
An aspirin added to the water would preserve the roses.
Flowers doesn't have to mean roses.
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 e2 e1 x1 x2 x3 x4.(n_rose(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))