在线路上禁止在道心、（）、岔尖和靠近车辆端部行走。
参考答案：轨枕头
but he still can not understand it.
A．Told many times
B．Having been told many times
C．He has been told many times
D．Though he has been told many times
气瓶阀门冻结时可用（）水解冻，严禁火烤。
A.100℃
B.80℃
C.40℃
