吊车中心柱的螺母可以不拧紧不拧靠。
参考答案：错
Would you please tell me _____ next, Mr Wang? [ ]
A. what should we do
B. we should do what
C. what we should do
D. should do what
CJ8Z一150Z型电磁接触器的额定电压为（）。
A、110V
B、220V
C、280V
D、380V
