a differential equation的用法和样例：
- Newton's second law can be expressed as a differential equation.
- The set of all solutions of a differential equation is called the complete or general solution.
- Designating a differential equation containing no more than two variables and derivatives of one with respect to the other.
- A differential equation of giving series of incremental AGC(Automatic Gauge Control)model has been derived by the error analysis method.
- A differential equation for calculating squeeze-film air damping in slotted plates is developed by modifying the Reynolds equation.