步进电机在转速突变时,若没有一个加速或减速过程,会导致电机_____。
A.发热
B.不稳定
C.丢步
D.失控
参考答案:C
---Do you know the famous scientist Yuan Longping?
---Of course. His name______whenever the matter of hybrid rice(杂交水稻)is discussed.
A.comes out
B.comes up
C.comes in
D.comes on
There _______ a big cake and many candies at the party yesterday.
A.was
B.were
C.is
D.are