n. any nonverbal action or gesture that encodes a message
n. any incitement to action
n. an electric quantity (voltage or current or field strength) whose modulation represents coded information about the source from which it comes
s. notably out of the ordinary
n. 信号, 暗号, 近因, 导火线
vt. 向...作信号, 标志, 用信号通知
vi. 发信号
a. 作为信号的, 显著的
[计] 信号
1. The teacher raised her hand to signal the end of the class.
老师举起手来示意下课结束。
2. He used a flashlight to signal for help in the dark.
他用手电筒在黑暗中发出信号寻求帮助。
3. The traffic light changed to green, signaling that it was safe to go.
红绿灯变成绿色，表示可以安全通行。