The meaning of a word is its use in the language.
一个词的意义在于它在语言中的使用。
采矿成功的关键在于可持续性——平衡经济增长与环境责任。
物体的加速度与所受的合外力成正比,与物体的质量成反比。加速度的方向与合力的方向相同。
Motivation is the art of getting people to do what you want them to do because they want to do it.