英语"减速"和"超速"怎么说

常见的英语"减速"和"超速"表达分别是 to slow down/to reduce speed 和 to drive over speed limit/to speed over limit。

除了上述动词表达，还可以用名词形式表达——

减速：slowing down，speed reduction

例：Slowing down/Speed reduction is required when driving through residential areas.

超速：over-speeding

例：Over-speeding will be fined.