(1)___________________________________________________.Compared with non-smokers they are more rebellious,their work becomes worse as they move up in school,they are more likely to leave school early and commit crimes,and are more often sexually mature.Many of these features can be summarized as anticipation of adulthood.There are a number of factors,which determine the start of smoking, and these are largely psychological and social.They include availability of cigarettes, curiosity, rebelliousness,appearing tough, anticipation of adulthood, social confidence, the example of parents and teachers,and smoking by friends and older brothers and sisters.It should be much easier to prevent children from starting to smoke than to persuade adults to give up the habit once established,but in fact this has proved very difficult.The example set by people in authority,especially parents, health care workers, and teachers, is of prime importance.(2)_______________________________________________.There is, however, a risk of children smoking just to rebel against the rules.And even in those schools which have tried to enforce no smoking by physical punishment,there is as much smoking as in other schools.(3)___________________________________________.Teachers too should not smoke at school, at least not in front of children.
