my solution is durable

來源: enchanted 於 2009-09-21 21:00:21 [] [舊帖] [給我悄悄話] 閱讀數 : (205 bytes)
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回答: 答第二題 由 transfer 於 2009-09-21 09:40:11

First, turn on two switches then go upstair
If light on, take out the bulb and come down. Measure if there still current go through the switch.
I admit it is not good as your answer but still durable

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