Therefore, keeping clean in workshop and regulating the metal constitution of rolling machine could reduce the Pb and Cu pollution during tea processing.

因此，保持加工场所的清洁卫生和调整揉捻机揉筒和揉盘的金属组成是降低茶叶加工过程中铅和铜污染的有效途径。

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Mr. Ratner explained that in 2005 Google had a small machine shop, metal tools, a wood workshop, and a welding workshop.

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