Final answer:
When a truck is following another truck or vehicle, it should keep a safe distance to allow at least two vehicles to enter safely between them.
Step-by-step explanation:
When a truck is following another truck or vehicle, it is generally recommended to keep a safe distance to allow at least two vehicles to enter safely between them. This is known as the two-second rule.
This distance is important to ensure that there is enough time and space for the following vehicle to react to any changes in the leading vehicle's movement. It allows for a buffer zone to avoid collisions in case of sudden braking or other emergency situations.
For example, if the leading truck or vehicle passes a certain point, the following truck or vehicle should not pass that same point until at least two more vehicles have entered the space between them.