直到1000多年前，出现了中国最早的纸币，交子。如今在中国使用的是第五套人民币。他在外观和技术上都有改进。The earliest paper money, named jiaozi, came out in China more than 1,000 years ago. Now the banknotes circulating in China is the 5th ____ of renminbi. The ____ and printing techniques _____ over the years.