求翻译：The proportion of world population living in urban areas surpassed 50% in 2008, and the rate of urbanization has continued rapidly ever since. With the worldwide population expected to grow further still, the issue of urban sustainability cannot be ignored. Urban dwellers demand increasing amounts of food, energy, and services, and the race to meet these demands can have great tolls on the natural environment as well as the human environment. In this seminar, we explore the meaning of urban planning and the three pillars of sustainability upon which it rests: environment, economics, and (social) equity. Issues we will focus on include environmental conservation, conventional and alternative energy sources, globalization, transportation, and housing equality. The seminar will begin on the global context, and then conclude with a focus on China, the most rapidly urbanizing country on earth at the moment.是什么意思？

待解决 悬赏分：1 - 离问题结束还有