题型:名词解释 Hearing the news about the crash of Air France Flight 447, he became very concerned _______ his daughter on board. A.inB.withC.aboutD.at 查看答案
题型:名词解释 如图所示,图线a是线圈在匀强磁场中匀速转动时所产生正弦交流电的图象,当调整线圈转速后,所产生正弦交流电的图象如图线b所示,以下关于这两个正弦交流电的说法错误的是[ ]A.在图中t=0时刻穿过线圈的磁通量均为零B.线圈先后两次转速之比为3:2C.交流电a的瞬时值为D.交流电b的最大值为 查看答案