unbalanced force的用法和样例：
例句
- Drinking too much can cause inarticulate, blurred vision, loss of balance force.
饮酒太多会造成口齿不清，视线模糊，失去平衡力。 - The action of a given force system on a rigid body remains unchanged if another balanced force system is added to or subtracted from the original system.
在已知力系上加上或减去任意一个平衡力系，并不改变原力系对刚体的作用。
