生理原则：
体育课：
Encouraging physical activity in the young through compulsory PE fights child obesity and contributes to forming lifelong habits of exercise.
体罚：
The actual physical damage inflicted via corporal punishment on children can be horrifying.
Some parents lose control and can injure children - even breaking bones or causing bruises.
禁烟：
There is little doubt that smoking tobacco is extremely harmful to the smoker's health.
配枪：
Routinely arming police officers allows them to defend themselves.