The traffic constable blows his whistle:
توضیح
A traffic controller uses a whistle to draw road users' attention so they notice and interpret the visible regulating gesture. The whistle is not, by itself, a command that every vehicle must stop.
A traffic controller uses a whistle to draw road users' attention so they notice and interpret the visible regulating gesture. The whistle is not, by itself, a command that every vehicle must stop.