  We study the influence of the reheating and equality transitions on
superhorizon density perturbations and gravitational waves. Recent criticisms
of the `standard result' for large-scale perturbations in inflationary
cosmology are rectified. The claim that the `conservation law' for the
amplitude of superhorizon modes was empty is shown to be wrong. For sharp
transitions, i.e. the pressure jumps, we rederive the Deruelle-Mukhanov
junction conditions. For a smooth transition we correct a result obtained by
Grishchuk recently. We show that the junction conditions are not crucial,
because the pressure is continuous during the reheating transition. The problem
occurred, because the perturbed metric was not evolved correctly through the
smooth reheating transition. Finally, we derive the `standard result' within
Grishchuks's smooth (reheating) transition.
