科学素养与生活应用·英语30篇（3）
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How a Light Switch Works
电灯开关如何工作
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A light switch controls electricity flow.电灯开关控制电流的通断。
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When you flip it up, the circuit closes.向上拨动开关，电路闭合。
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Electricity then moves to the light bulb.电流随即流向灯泡。
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The bulb turns on and gives light.灯泡亮起，发出光亮。
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When you flip it down, the circuit opens.向下拨动开关，电路断开。
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No electricity flows to the bulb.电流不再流向灯泡。
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The bulb turns off and stays dark.灯泡熄灭，保持黑暗。
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This simple device uses basic engineering.这个简单装置运用了基础工程原理。