Why do some areas test negative for chlorine?

为什麽有些区域的氯测试为阴性？

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For the moment, the suggestion is that those who test negative should get a second opinion.

目前，对那些被检测为成阴性的女性的建议是她们应该进行第二意见咨询。

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Meteorological and laboratory areas, such as gauge or weight measurement must also test negative pressure, vacuum and so on.

气象及实验室等领域进行表压或绝压得测量，也可测负压，真空度等。

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The U.S. Environmental Protection Agency's drinking-water regulations require that all samples test negative for E.coli.

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Those who test negative for a serious and costly disease may drop coverage, while those who test positive may add or increase coverage.

ECONOMIST: Genetics, medicine and insurance

If you test negative for this potentially serious condition, then you can begin a trial to see just how gluten-sensitive you are, if at all.

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