半自动闭塞电气集中车站，超长列车头部越过出站信号机而未压上出站方向的轨道电路，行车凭证为路票。
参考答案：错
Bricks covered the ground like red autumn leaves. No wind, _____, could blow them away. [ ]
A. but
B. besides
C. however
D. except
国产钢丝绳现已标准化，定规定了钢丝的抗拉强度分为（）等级。
A.4个
B.5个
C.6个
D.7个
