It's usually insulated by a thick layer of rubber, but if the wire is frayed, damaged, or loosened, it can expose electrically "hot" metal to the tangle of cables and dust behind your equipment.
通常电源线外面都包裹一层厚厚的橡胶。若一旦这层橡胶磨损、损坏或者松脱了，那么里层金属可就和电器后面那些线缆以及灰尘通上电了。
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