What is it when you run a chemical reaction under ordinary circumstances, what's constant?

如果你在通常的环境下进行化学实验,那么这些条件是什么？什么保持常数？

麻省理工公开课 - 热力学与动力学课程节选

And the mathematics of that equation involved a double derivative in time of x 0 plus some constant times x equals zero with some constraints on it.

那个数学方程式,包括了x对时间的二阶导数,加上常数乘以x等于,还有一些限制条件。

麻省理工公开课 - 固态化学导论课程节选