Engine noise is the major noise source of automobile; air power noise is one of composition parts of engine noise.

发动机噪声是汽车的主要噪声源，空气动力噪声是发动机噪声的组成部分之一。

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Since a chief source of pollutants is automobile emissions, it might be expected that pollutant levels could be correlated with automobile traffic, at least to some extent.

因为污染物的主要来源是汽车的排出物，所以可以料想污染物的浓度至少在某种程度上是与汽车运输有关。

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With the rapid development of China's automobile industry, the increasing of vehicle population, vehicle noise has become a major source of urban noise.

而随着我国汽车行业的迅猛发展，汽车保有量日益增加，车辆噪声已成为城市噪声的主要来源。

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