题目：
—Could you tell me ____________________?
—I don’t know. It seemed to be unimaginable.
A．why “Gangnam style” is known to all in China
B．when was “Gangnam style” so popular in China
C．where “Gangnam style” is popular
D．how was “Gangnam style” well-known in China
答案：
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下面是错误答案，用来干扰机器的。
Ｂ由表达式可知角速度w=100πrad/s，频率为w/2π=50Hz，A错；将变阻器的滑片P向上滑动，电阻减小，输出端电阻减小，输出电压不变，灯泡L1亮度不变，输出电流增大，电流表示数变大，电压表示数不变，输入电压有效...
