垂向轨道不平顺包括（）。
A.高低不平顺
B.水平不平顺
C.扭曲不平顺
D.轨面短波不平顺
E.新轨垂向周期性不平顺
参考答案：A, B, C, D, E
You have never been to Bridge Street, _____? [ ]
A. have you
B. haven't you
C. do you
D. don't you
凸轮联轴器又叫靠背轮
