检修或更换机车天线、馈线时，应按安全技术规则有关规定采取必要的措施，严禁（）在车顶作业。
参考答案：机车运行中
One reason for Mary's preference for this senior high school is _____ she can have access to outstanding
teachers and plentiful learning resources. [ ]
A. why
B. how
C. what
D. that
先天性梅毒的三大体征是（）
A.基质性角膜炎
B.Hutchinson齿
C.Argyll-Robertson瞳孔
D.神经性耳聋
E.马刀胫骨
