— ?
—He fell in the mud.[ ]
A. What is it
B. What can it do
C. What happened
答案:C
电压损失是指线路始末两端电压的数值差
在释压状态未被解除之前,要提醒旅客停止一切活动,但乘务员应在客舱内走动,并让旅客消除疑虑。()