Abegg's rule of eightn的用法和样例：
- I did the calculation by the rule of three.
- She made a rule of eating an apple a day.
- The rule of thumb in this business is courtesy.
- People rose up against the despotic rule of their potentate.
- By breaking the rule of absolute secrecy, he became a marked man.
- A teacher's most basic rule of thumb is: be patient.