the Great Wall; 长城
outside the city [city wall] 城外
the eastern [western] part of the city; 东[西]城
inner [outer] city 内[外]城
the difference between town and country; 城乡差别
the interflow of commodities between the urban and rural areas 城乡商品交流
Cheng Hun 城浑
牛津高阶第八版
美国韦氏词典
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维基百科 (自由的百科全书)