disaster: implies an unforeseen, ruinous and often sudden misfortune that happens either through lack of foresight or through some hostile external agency: the war proved to be a ~ for the country.     misfortune不幸unhappy change of fortune，是不幸misfortune-adversity组的首词，一般比较严重


catastrophe: implies a disastrous conclusion and emphasizes finality: speculation about the ~ that befell Atlantis.


calamity: stresses a grievous misfortune involving a great personal or public loss: the father's sudden death was a ~ for the family.   grief悲痛=poignant sorrow


cataclysm: originally refers to a deluge or geological convulsion, applies to anything that produces an upheaval or complete reversal of an existing order: the French Revolution ranks as one of the ~s of the modern era.    catastrophe和cataclysm有相同词根CATA，表示down，disaster中的aster表示星星，DIS词根表示apart, opposite, not离开相反否定


disaster灾难: 指未曾预料、毁灭性的、突发的不幸，catastrophe灾难: 指灾难性结果、强调终结，calamity灾难: 强调个人或公众损失令人哀恸，cataclysm灾难: 原指洪水地震，现指动荡和颠覆


记忆方法: 1) 首字母DCCC想成CCCD常常冲动<==招致灾难
   
         2) 灾难的意思是可怕的不幸(事件或状况)mean an event or situation that is or is regarded as a terrible misfortune. 首字母DCCC想成CCCD常常冲动<==招致灾难