从前人的成果，即以人口表示的城市位序-规模法则和以建成区面积表示的位序-规模法则出发，演绎出城市的用地规模和人口数量呈异速增长。
We start at the rank-size rule by urban population and the rank-size rule by urban built-up area, and derive a mathematical relationship that the land use size of a city and its population.
如何用二重积分来表示面积呢？
辐射剂量，用西弗茨表示，按辐射的类型和身体被辐射的面积进行计算。
Radiation doses, measured in sieverts, are calculated by taking into account the type of radiation and the area of the body that has been irradiated.
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