答案:const int TrigPin = 2;Const int EchoPin = 3;Void setup() {Serial.begin(9600);PinMode(TrigPin,OUTPUT);PinMode(EchoPin,INPUT);Serial.println("Ultrasonic sensor:");}Void loop() {DigitalWrite(TrigPin,LOW);DelayMicroseconds(2);DigitalWrite(TrigPin,HIGH);DelayMicroseconds(10);DigitalWrite(TrigPin,LOW);Distance = pulseIn(EchoPin,HIGH)/58.00;If(distance < 15)Tone(6,1000);ElseNoTone(6);Serial.print(distance);Serial.print("cm");Serial.println();Delay(1000);}