题干
Despite the warm personal relations with Hu, Bush admitted that ___ differences remain between the two countries, which makes ____ dialogue imperative.
A：the; a
B：the; /
C：/; a
D：/;/
答案(点此获取答案解析）
C
，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