unbalanced force的用法和樣例：
例句
- Drinking too much can cause inarticulate, blurred vision, loss of balance force.
飲酒太多會造成口齒不清，視線模糊，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.
在已知力繫上加上或減去任意一個平衡力系，並不改變原力系對剛體的作用。
