If your smoke detector is working properly, the red light should be on.
如果你的烟雾探测器运作正常，红灯应当亮起。
These apertures restrict the amount of light that can reach the detector.
这些光阑将会限制到达探测器的光线的总量。
Typical absolute standards include two types: absolute standard detector and absolute standard light source.
常用的绝对标准有两类：绝对标准探测器和绝对标准光源。
Typical absolute standards include two types: absolute standard detector and absolute standard light source.
常用的绝对标准有两类：绝对标准探测器和绝对标准光源。
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