【单选题】
As a teacher, you should not _______ the students from asking questions in class.
【单选题】
Earthquake survival supplies include a torch, a spade, some rope and a radio ____.
【单选题】
The engineers in this lab spent several weeks _______ their plans for the new bicycle.
【单选题】
Had he worked hard, he _____ the exams.
【单选题】
居民户外晒衣绳应至少与10kV电力线路保持多少米的水平距离。
【单选题】
已知某电动机的同步转速为1500r/min,其转子转速有可能是( )r/min。