Students are tired of doing the same exercise ________.A. day by day B. day after dayC. day to day D. day before day 答案:【答案】B【解析】句意:学生厌倦日复一日地做同样的练习。day by day日渐;一天天地;day after day一天又一天,日复一日;day to day天天;这里是说日复一日。故选B。在一个正常工作的理想变压器的原、副线圈中,下述哪些物理量在数值上不一定相等
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A.交变电流的频率
B.交变电流的功率
C.交变电流的最大值
D.端电压的有效值