The rock breaking without smoke,dust,slungshot,noise and any internal injury can reduce environmental pollution and energy consumption,which has great economic value and social sense.
As long as snowballs were the only weapon, no one was much hurt, but a stone may be put in a snowball, and in the dark a stick or a slungshot in the hands of a boy is as effective as a knife.
烟、
、
石,
的教育（上）
大伤害，但可以在雪球
放入一块石头，在黑暗
手
