一则寓言讲，一只山猪在大树旁勤奋地磨獠牙，狐狸好奇地问：既没有猎人来追赶，也没有任何危险，为什么要这般用心地磨牙？山猪答道：一旦危险来临就没有时间磨牙了，现在磨利了到用的时候就不会慌张。的确，未雨绸缪，多点忧患意识，才能更好地生存；多学些知识和本领，提高 A parable says that a wild boar grinds his teeth hard at the tree. The fox curiously asks, "There is no hunter to catch up and there is no danger. Why should we grind so hard? Mountain pig replied: once the danger comes there is no time to molars, and now the time to use will not be scared. Indeed, to take precautions, more sense of crisis, in order to better survive; learn more knowledge and skills to improve