An aspirin added to the water would preserve the flowers.
The flowers are 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 p1 x1.(n_flower(x1) & exists x2.((x1 = x2) & n_rose(x2)))