进站、出站、进路信号机，当（）时，均视为停车信号。
A、灯光熄灭
B、显示不明
C、显示不正确
参考答案：A, B, C
It is usually not quite cold in this area in March, but sometimes temperature________ be very low.
A．should
B．can
C．must
D．shall
影响病原物的侵入途径有哪些？
