精选优质文档-倾情为你奉上1. Atlantic to Pacific1. the diversity of the physical conditions in the United Statesin its vast area, the United stated comprehends most of the physical conditions know to men: heat and cold, forest and desert, tropical swamp and Arctic waste, mountains and endless plains, empty spaces and megalopolis, and the worlds largest river system.2. the diversity of the people in the United StatesDiversity of the people themselves is immense: people come from the different c