equilibrium of forces

例句：

1. 1. The weight of the earth is what keeps the planet in equilibrium.
   地球的重量是保持星球平衡的关键。
2. 2.The scientist found that the equilibrium between oxygen and nitrogen gases was disturbed by the addition of a small amount of water.
   科学家发现，氧气和氮气之间的平衡被少量水加入时被打破。
3. 3. The equilibrium of the two forces was such that neither could move without the other's support.
   这两种力量的平衡是如此稳定，以至于它们不能单独移动，需要彼此的支持。