The news reporters hurried to the airport, only         the film stars had left. [ ]

A. to tell

B.told

C. telling

D. to be told

（1）当开关掷向1时，电压表示数为3V，此时电阻箱的电阻为6Ω，求R₂上电流在1min内产生的热量是多少？

（2）当开关掷向2时，灯泡恰好正常发光，电压表读数为原来的2倍，求灯泡的额定电压和额定功率。