**Reversing** is prohibited on all roads, except in specific situations where it is necessary as part of another maneuver. These exceptions include:

- **Parking the vehicle**: You can use reverse to park.

- **Inability to move forward**: If you cannot move forward or change direction, such as when exiting a street blocked by construction, you can reverse.

On highways and expressways, reversing is **always prohibited**. Additionally, when making a **U-turn**, reversing should not be used unless there is no other viable option, such as in a dead-end street. Therefore, the correct answer is that reversing is prohibited on all roads, except as a complementary maneuver required by another.