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【单选题】
PLC 输入模块的故障处理方法正确的是 ( ) 。 1 有输入信号但是输入模块指示灯不亮时应检查是不是输入直流电源的正负极接反 2 若一个 LED 逻辑指示灯变暗,而且根据编程器件监视器,处理器未识别输入,则输入模块可能存在故障 3 指示器不亮,万用表检查有电压,直接说明输入模块烧毁了 4 出现输入故障时,首先检查 LED 电源指示灯是否响应现场元件(如按、行程开关等)A.
①②③
B.
②③④
C.
①②④
D.
①③④
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【单选题】(听力对应练习）How often does Tracy goes to the movies?
A.
twice a week
B.
once a week
C.
Not very often
【单选题】Tracy often listen to music in her spare time.中listen to music的中文意思是:
A.
听收音机
B.
听音乐
C.
打篮球
D.
/
【单选题】--- What do you often do_______ classes to relax yourselves? --- We often do eye exercises, listen to music or do some running around the school.
A.
in
B.
among
C.
between
D.
during
【单选题】—Don't you often listen to _____ rad io? —No. In fact, I haven't _____ radio . [ ]
A.
a ; an
B.
/ ; the
C.
an; /
D.
the; a
【简答题】嘧啶环上的第____位氮原子与戊糖的第____位碳原子相连形成____键,通过这种键相连而成的化合物叫____。
【单选题】The music ________ nice. I often ___________ it.
A.
listen to / sound
B.
hears / listen to
C.
listens to / listen to
D.
sounds / listen to
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