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.
的过程中,
烟、
环境污染,降低能耗。
到
大
，
可以在雪球中放入一块石头，在黑暗中，男孩手中的棍子或弹弓与刀一样有效。
