“恒定的”用英语怎么说？

在相同的条件下,分子速度分布在任何时候都是恒定的.At any given instant the distribution of molecular speeds is always constant under the same conditions.它使火车在通过现有轨道的弯曲处时得以保持恒定的车速。It allows the train to maintain a constant speed through the twist...