电动机的工作状态有哪四种？
参考答案：
电动状态、反接制动、再生发电制动、单向制动状态。
When we visited Zhou Zhuang again ten years later, we found it changed so much that we could hardly ________ it.
A．request
B．recognize
C．swap
D．realize
甲车2小时行100千米，乙车3小时行180千米，甲、乙两车的速度比是______．
