【判断题】DS-32时间继电器的线圈是短时工作制,当需长期工作时需串入限流电阻。
【判断题】Social mobility has changed since the 1970s and in some ways has got better.
【判断题】With the changes in class division and social mobility, people's attitude to accent has become more rigid.
【简答题】Americans are reputed to be friendly people. Their friendships, however, tend to be shorter and more casual than friendships among people from other cultures. It is not uncommon for Americans to have ...
【判断题】Social mobility has changed since the 1970s and in some ways has got better.
【简答题】步进电机是将电脉冲信号转变为角位移或线位移的开环控制元件。 电机的转速和停止的位置只取决于的( )和( )