() is an electronic component made of semiconductor material.
A. resistor
B. transformer
C. PN junction
D. transistor
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A small current flowing from the () to the emitter can control a much larger current between the collector and emitter terminals.
A. base
B. gate
C. P type semiconductor
D. N type semiconductor
When reverse-biased, an ideal () would block all current. A real one lets perhaps 10 microamperes through–not a lot, but still not perfect.
A. forward
B. switch
C. resistor
D. diode
电梯的有齿曳引机通过与蜗杆相连,涡轮与曳引轮同装在同一根轴上,曳引绳挂在曳引轮上。
A. 联轴器
B. 花键
C. 轴
D. 离合器
电梯的电磁制动器安装在高速轴靠近的一侧,与曳引电动机之间有连轴器相隔。
A. 蜗杆
B. 涡轮
C. 曳引轮
D. 导向轮