In which two situations is it recommended to downshift?

Downshifting is an important technique used to maintain control and stability of a vehicle during specific driving situations. The recommended situations for downshifting in this case are before entering a curve and before starting down a hill.

When entering a curve, downshifting helps to reduce speed and allows for better handling of the vehicle. By shifting to a lower gear, the engine provides greater power and responsiveness, which is crucial for navigating turns safely, particularly if the curve is sharp or if road conditions are less than ideal.

Before starting down a hill, downshifting is vital for engine braking. Engaging a lower gear increases the engine's resistance to the drive wheels, allowing the vehicle to slow down naturally without relying solely on the brakes. This technique helps prevent brake overheating and prolongs the life of the braking system, ensuring that the driver maintains better control of the vehicle as it descends.

The other scenarios listed do not align as well with the best practices of downshifting. While it’s important to adjust speed when approaching traffic signals or turning, these actions don’t specifically require the technique of downshifting to the same degree as negotiating curves or descending hills.