自动闭塞区间通过信号机显示停车信号（包括显示不明或灯光熄灭）时，列车必须在该信号机前（）。
参考答案：停车
It was my sister ________ first had the idea to cycle along the entire Mekong River.
A．who
B．whom
C．/
D．which
失真
