A. 自动闭塞 B. 半自动闭塞 C. 自动站间闭塞 D. 电话闭塞
A. 物理干扰 B. 化学干扰 C. 电离干扰 D. 磁场干扰
A. would not die B. could not have died C. might not die D. should not have died