It generates simple substance arsenic by reduction reaction in the colloid system with the existence of protection agent that plays a role of bi-template, dispersing and stabilizing simple substance.

其制备方法是在保护剂存在的胶体体系中，将砷化合物加还原剂还原形成单质砷。

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For the corrosion of bronze by the soil, water and chloride and its easily corrosionspreading, the bronze protection agent for harmful erosion conversion is studied and produced.

针对青铜器受土壤、水、氯化物等的侵蚀而产生锈蚀且容易蔓延的特点，研制出青铜器有害锈转化剂和青铜保护剂，可将有害锈转化为无害锈，然后再进行保护。

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The father had also contacted people explaining that he was a secret agent who was leaving as part of a witness protection programme.

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The Environmental Protection Agency has classified secondhand smoke as a known human cancer-causing agent.

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" Hector Gonzalez, an FBI supervisory special agent, is more blunt: "Many of these criminals are hiding behind governments for protection.

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