（新华社北京2月25日电 记者朱基钗、胡浩、丁小溪、高蕾、胡梦雪）
Viren Swami believes today's ideas about romantic love can be traced back to medieval European stories like Lancelot and Guinevere
。51吃瓜对此有专业解读
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.
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