这句话中好多数字怎么翻译？数字为什么加复数？
Mister Friedman advised President Richard Nixon and President Ronald Reagan in the nineteen seventies and eighties. He played a part in pulling the United States out of a period of high unemployment and inflation in the nineteen seventies.
那些数字都是什么意思？为什么加复数？
参考答案:nineteen seventies and eighties就是1970s and 1980s意思是20世纪70和80年代