#include<reg51.h>void delay(unsigned int z) //声明延时函数sbit beep=P2^7 void main()数{ while(1){ beep=0 //蜂鸣器响 delay(1) //调用1ms延时 beep=1 //蜂鸣器不响 delay(1) //调用1ms延时 }}void delay(unsigned int z)//1ms延时，通过z值改变延时{ unsigned int x for( z>0 z--)