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最佳答案:解题思路:(1)LED灯额定电压为2.5V,测10个LED灯正常发光时的功率.供电电源是2节干电池,电压为3V,要使10个LED灯并联.(2)闭合开关前,滑片处
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最佳答案:LED light bulbs for indoor lighting purpose has not significant advantages over