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.
自从他的悼词之后，我没有再公开谈论我与乔布斯的友谊、冒险与合作。我从未去读那些铺天盖地的故事、讣告，或那些奇怪的误读如何被写进「传说」。
，详情可参考safew官方下载
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You can set up Privacy Display to activate when you're asked for a password or PIN, or when you get a notification or open certain apps. So if (for instance) you tend to look at your banking apps when you’re on public transit and don’t want other passengers to see how much moolah you have, Privacy Display seems like a very handy feature.