【简答题】步进电动机是用 信号进行控制的,其转速大小取决于控制绕组的脉冲频率、 和 ,而与 、 、 等因素无关,其旋转方向取决于 控制绕组的 轮流通电的顺序。
【单选题】Why did the man take the job at the travel agency?
A.
He wanted to go to Spain.
B.
He wanted to work with his friend.
C.
He enjoyed travelling around the world.
D.
He was rejected by the engineering firm.
【单选题】He left school after taking 0-levels because ______.
A.
he did not enjoy school
B.
he wanted to work with computers and staying at school did not help him
C.
he was afraid of getting too old to start computing
D.
he wanted to earn a lot of money
【单选题】OSI 参考模型将网络的层次结构划分为 。
【多选题】在子类中对父类方法进行重写时,要求子类中重写的方法需要和父类被重写的方法具有相同的( )
【简答题】步进电动机是用 信号进行控制的,其转速大小取决于控制绕组的脉冲频率、 和 ,而与 、 、 等因素无关,其旋转方向取决于 轮流通电的顺序。
【简答题】步进电动机是用 信号进行控制的,其转速大小取决于控制绕组的脉冲频率、 和 ,而与 、 、 等因素无关,其旋转方向取决于 的轮流通电的顺序。