A study on the eco-economic development model in the eco-environmental vulnerable and needy region on Loess Plateau: the case of Dingxi Prefecture in Gansu Province是什么意思_A study on the eco-economic development model in the eco-environmental vulnerable and needy region on Loess Plateau: the case of Dingxi Prefecture in Gansu Province在线翻译_英语_读音_用法_例句