某同学做“测量小灯泡电功率”实验中，所用电源电压恒为4V，小灯泡的螺旋套上标有“2.5V”字样

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       Both the British and Americans speak English. However, there are several differences between American English and British English. For example, the words they use in daily life are not the same. The British call the first floor of a building the ground floor. The floor above the ground floor is the first floor, which Americans call the second floor. Once you go to Britain and America, you may notice other differences. The British usually hide their feelings. They don't often start a talk with strangers. On the train the British often spend their time reading newspapers or books. But Americans are more active and easier to talk with.

瘦肉精是一类对人体健康危害极大的化学物质，政府已严禁在猪饲料中添加瘦肉精。常见的瘦肉精化学式为C₁₂H₁₈OCl₂N₂，下列有关这种瘦肉精的说法中正确的是（  ）