[xìn hào]
signal; semaphore; gun
an audible signal
音频[响]信号
semaphore
臂板信号{铁道}
light signal
灯光信号
identification signal
识别信号
distress signal; SOS
遇难信号{航海}
hash
杂乱信号{无}
A train must not pass a signal that is at danger.
火车切不可越过危险信号。
Signals are made with flags or lamps.
信号是用旗或灯发出的。