—Did you have a good time?

—It couldn't be worse. We were held up on the expressway for three hours. On the way back, we found the car got a f____ tyre, and the spare was, too.

肥胖可能会引发许多慢行疾病，某人用如图所示的健身拉力器进行减肥锻炼，配重由若干金属块（每块质量为10kg）组成，锻炼时可以根据自己的实际选择配重的金属块数量。（杆重、绳重、摩擦均不计，g取10N/Kg）

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（  ）