接触器的吸合线圈在电源电压为线圈额定电压值的（）时，能可靠工作。
A、40%
B、80%
C、85%～105%
D、60%
参考答案：C
A．0.02A
B．0.2A
C．2A
D．20A
The dancers, all of _______ masks came off suddenly, gave us a great surprise. [ ]
A. their
B. whose
C. which
D. whom
