Final answer:
When changing lanes on a multi-lane road, it is important to check the lane next to you and the lane behind you.
Step-by-step explanation:
When changing lanes on a multi-lane road, it is important to check the lane next to you and the lane behind you. This ensures that there are no vehicles in your blind spot or approaching at high speed. Checking the lane in front of you is also important, especially for determining if there is enough space to safely merge into the new lane.