Study on the impact of population aging on the structure of import and export trade Research on the impact of population aging on technological progress Cases and problems solving to the practice on import and export trade Study on the natural capital embodied in China's import and export trade Analyse on the impact of RMB's exchange rate volatility on China's import and export trade Research on the impact of population aging on economic development in China 并列题名：Cases and problems solving to the practice on import and export trade 并列题名：Analyse on the impact of RMB's exchange rate volatility on China's import and export trade