Final answer:
It is safe to return to the right-hand lane after passing another vehicle when you can see the passed vehicle in your rearview mirror and have enough clearance to return safely.
Step-by-step explanation:
When passing another vehicle, it is generally safe to return to the right-hand lane once you can see the passed vehicle in your rearview mirror and have enough clearance to return safely without cutting off the other vehicle. It is important to use your turn signal and check blind spots before merging back into the right lane.
For example, if you are driving on a two-lane road and pass a car traveling at a slower speed, you should wait until you have a clear view of the passed vehicle in your rearview mirror and there is sufficient space between you and the passed vehicle before moving back to the right lane.