Optional temperature sensing can be added for additional system monitoring and control.

可选的温度传感器部件可以作为检测和控制系统的补充。

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The CM system can also create and maintain a full-text index of the archived objects (optional setting).

CM系统还可以创建和维护被归档对象的一个全文本索引(可选设置)。

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Although this is optional, it is a good test to check that the system has been configured correctly.

虽然这是可选的，但是可以很好地检查系统是否配置正确。

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An optional global positioning system unit encodes geographical meta data into your photos.

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Cadillac superserves drivers in a hurry with its optional Easy Key system, enabling passive vehicle and trunk entry and keyless ignition via a personalized keyless fob.

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The company points to a recent Dev Center document emphasizing Windows 8's optional app receipt system, which can require any transaction be validated on the developer's server.

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