Why we should change the speed limit on certain roads?

Certain roads run along different areas.

For example, slow speeds are required for safety is a road is near a school or in a neighborhood, because pedestrians may be walking across the road.

On a highway, no pedestrians will be there (hopefully) so higher speeds can be safely used.

Another example of using a slow speed is on a rocky or rough road, so the vehicle does not accidentally lose control.

To summarize: different roads have different speeds depending on the use of the road, these different speeds are often enforced for safety.

I hope this helped.

ń, wǒ shuō yīngyǔ, dàn wǒ huì shuō qítā yǔyán, rú xībānyá yǔ fǎyǔ yìdàlì yǔ hé pǔtōnghuà, suǒyǐ bùyào pànduàn, dànshì