精选优质文档-倾情为你奉上Unit 1 The Evolution of Transport交通工具的演化The evolution of transport has been closely linked to the development of humankind throughout the earths historyTransports early function was to meet the basic need of hauling food supplies and building materialsBut with the formation of tribes，then peoples，and finally nations，the societal and economic functions of transport became more and more complex. At first there was mobility required for individuals，clans，households，and
