已知灯L1的额定电压为U,额定功率为P1;灯L2的额定电压为2U,额定功率为P2。若将两灯串联接在电压为U的电源上,此时灯L2消耗的电功率为_________。
— Do you know Henry didn't win that speech contest?
— _____? I thought he would. He worked so hard on it. [ ]
A. Do I
B. Don't I
C. Did he
D. Didn't he
蒸汽过热器的用途是什么?