题干
129. After a long riding, the passengers in the bus were very tired and some of them ____ asleep.
A：went to
B：fell
C：put to
D：Became.
答案(点此获取答案解析）
B
A：went to
B：fell
C：put to
D：Became.
，副线圈中接有定值电阻R。当原线圈从AC端输入电压为U的正弦交流电压时，原线圈中电流为I，电阻R上消耗的功率为P。当原线圈从AB端输入电压为U的正弦交流电压时，原线中电流为
，电阻R上消耗的功率为
。那么