【单选题】题: 常用于起重机械在位能负载作用下和多速异步电动机由高速转为低速时的情况下制动方法是()
【简答题】我们专营上述业务。,我们同你们国家就上述商品做过大笔交易。 We are _______ the above business and recall that many years ago, considerable business was done________ on such items.
【判断题】已知 ord('A')==65 返回True,故 ord('A')-65==0 也返回True
【单选题】世界上第一台数控机床诞生年代是( )。[单选题]
【简答题】我们专营上述业务,,我们同你们国家就上述商品做过大量交易。 We _______ the above business, many years _____, considerable/a lot of business was done ________ on such items.
【单选题】关于电动机的制动方法描述中,正确的是( )
B.
反接制动属于电气制动方法,不可以实现准确停车,若不及时切断电源会造成电动机反向转动
C.
常用的电气制动方法有反接制动,能耗制动和电磁抱闸制动
D.
常用的电气制动方法有反接制动,能耗制动和电磁离合器制动
【简答题】我们专营上述业务,,我们同你们国家就上述商品做过大笔交易。 We _______ the above business many years _____, considerable business was done________ on such items.