Now, the VOA Learning English program, Words and Their Stories. Different people have different ways of saying things – their own special expressions. Each week we tell about some popular American expressions. What you are listening to is a call for help. It is the Morse code distress signal S.O.S. For years, telegraph operators used Morse code to communicate across the country and around the world.___________________________现在是美国之音慢速英语词汇掌故节目. 不同的人都有他们自己独特的词汇.每周我们都会讲述一些美国常用词汇. 今天你将听到的是摩斯电码求救信号S.O.S.世界各地的电报员们多年来一直使用莫斯电码交流.___________________________