居安思危

居安思危 　　Explanation: Although in a safe environment, but also think of a dangerous possibility. That at any time be mentally prepared to cope with unexpected events. 　　Usage: Joint type; as the predicate attribute, object; with compliment 　　Source: Pre Hengyu "Zuo Xianggong ten year": "" book ", saying: 'be prepared', thought is well prepared, be prepared for." 　　Examples: Graces think shame, ~ (Qing Qian Cai, "said Yue Fei," sixty-back) Thesaurus:  Security risk not forget, sharpen [heighten] one's vigilance, bend the chimney and remove the fuel to prevent a possible fire