The wire must be free from contamination, rust and mechanical damage.

钢丝表面无污染, 锈蚀和机械损伤.

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Then, most important of all, the water must be made free from contamination from sewage.

而最重要的是必须使水免于污水的污染.

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Free from contamination, safe, high grade, nutrition kind food gets the favour of people.

无污染 、 安全 、 优质 、 营养类食品受到人们的青睐.

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