【单选题】My uncle comes home very late in the evening. He is very _____. [ ]
【简答题】Mr. Read works in an office. He is very busy and has no time to have a good rest. Every evening, when he comes back from his office, he’s always tired and wants to go to bed early. But his wife often ...
【单选题】( )光电开关就产生了检测开关信号。
D.
( D)当被检测物体经过且完全阻断光线时
【判断题】当被检测物体经过且发射器停止振荡时光电开关就产生了检测开关信号。
【简答题】busy evening very this We're