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Optical-based smoke alarms use light instead. They are slightly better at detecting the large smoke particles created by slow, smouldering fires. When such particles enter a chamber in the device, they scatter light from a small light source, which is then picked up by a photoelectric sensor.
，更多细节参见下载安装汽水音乐
The crew of the ill-fated Apollo 13: Jack Swigert, Jim Lovell and Fred Haise
「（企業）對政策不斷改變感到沮喪與挫折。」
Москвичей предупредили о резком похолодании09:45