The static modifier that precedes $onlyOne ties the variable to the class itself.

$onlyOne 之前的静态修饰符将此变量关系到类本身。

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The $onlyOne variable is said to be a class attribute, as it is scoped to the class.

$onlyOne变量是一个类属性，因为其作用域是这个类。

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RealMeter represents the highest industrial-level, especially for some famous helium leak detector brand. RealMeter is the onlyone whose maintenance can be done at the circuit level in China.

睿米的氦质谱检漏仪维修，代表着国内最高水平。我们的维修可以做到电路级别，质谱室级别，国内唯一。

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RealMeter represents the highest industrial-level, especially for some famous helium leak detector brand. RealMeter is the onlyone whose maintenance can be done at the circuit level in China.

睿米的氦质谱检漏仪维修，代表着国内最高水平。我们的维修可以做到电路级别，质谱室级别，国内唯一。

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