keep: suggests a customary or wonted noticing without anything untoward or inappropriate: ~ the Sabbath.   untoward反常异常unexpected, especially unpleasant，inappropriate不恰当，这两个词在这里表示纪念没有不妥之处，没有译出         安息日(犹太教定为星期六，基督教定为星期日)


observe: suggests marking the occasion by ceremonious performance of required acts or rituals: not all holidays are ~d nationally.


celebrate: suggests the acknowledge of an occasion by festivity or indulgence: traditionally ~s Thanksgiving with a huge dinner.


commemorate: suggests the marking of an occasion by observances that remind one of origin and significance: ~ Memorial Day with the laying of wreaths.


keep遵守(传统等): 习俗性注意遵守，observe庆祝: 举行仪式，celebrate庆祝: 欢庆欢宴，commemorate纪念: 唤起起源意义的仪式


记忆方法: 1) 首字母COCK公鸡，想成宝鸡<==纪念     唐肃宗至德二年（757年），地方奏报闻陈仓山有神鸡鸣叫，肃宗以为神鸡鸣是祥瑞之兆，下旨将陈仓县改为宝鸡县      通常说的过节庆祝，实际是怀念或敬意，这组词的基本意思是纪念

         2) 纪念的意思是对某一事迹表达怀念或敬意mean to notice or honor a day, occasion, or deed.首字母COCK公鸡，想成宝鸡<==纪念