This essay tries to analyse the four main sources. If agricultural pollution, at the same time, point out some specific prevention measures.

就农业污染的四个主要来源进行分析，并提出具体防治措施。

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This paper analyses the four main causes leading to the average accidents and puts forward four relevant precaution measures for the sake of enhancing safe management to the fishing boats.

本文从加强渔船安全管理的角度出发，分析产生海损事故的四个主要原因，并提出四项防范措施。

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Four measures to prevent tooth decay one, oral health: The main aim is to remove plaque.

四种预防蛀牙的对策一、口腔卫生：主要目的是去除牙菌斑。

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