精通break语句的看过来

#include<reg52.h>
sbit P1_1=P1^1;//左
sbit P1_0=P1^0;
sbit left=P2^0;
sbit middle=P2^1;
sbit right=P2^2;
void delay_nus(unsigned int i)
{
   i=i/10;
   while(--i);
}
void delay_nms(unsigned int n)
{
  n=n+1;
  while(--n)
  delay_nus(900);
}
void initial(void)
{
  IE=0x82;
  TCON=0x00;
  TMOD=0x02;
  TH0=0x38;
  TL0=0x38;
  TR0=1;
}
void left_turn()//大转
{
    P1_1=1;
    delay_nus(1300);
    P1_1=0;
    P1_0=1;
    delay_nus(1300);
    P1_0=0;
    delay_nms(20);
}
void leftturn()//小转
{
    P1_1=1;
    delay_nus(1550);
    P1_1=0;
    P1_0=1;
    delay_nus(1300);
    P1_0=0;
    delay_nms(20);
}
void right_turn()
{
    P1_1=1;
    delay_nus(1700);
    P1_1=0;
    P1_0=1;
    delay_nus(1700);
    P1_0=0;
    delay_nms(20);
}
void rightturn()
{
    P1_1=1;
    delay_nus(1700);
    P1_1=0;
    P1_0=1;
    delay_nus(1450);
    P1_0=0;
    delay_nms(20);
}
void forward()
{
    P1_1=1;
    delay_nus(1700);
    P1_1=0;
    P1_0=1;
    delay_nus(1300);
    P1_0=0;
    delay_nms(20);
}
void backward()
{
    P1_1=1;
    delay_nus(1300);
    P1_1=0;
    P1_0=1;
    delay_nus(1700);
    P1_0=0;
    delay_nms(20);
}

int main()
{
    initial();
    while(1)
    {
        switch(P2&0x07)
        {
        case 0:
        
            do
            {
            backward();
            left_turn();//打转}
            while(P2&0x07==0)
                    
             break;
        case 1:
            
                do                    
            left_turn();
            while(!P2&0x02)
            break;
        
        case 2:
            
                do
            forward();
            while(P2&0x02)
        
             break;
        case 3:
        
                do
            leftturn();
            while(P2&0X01)
              break;
                    
        case 4:
            do
            right_turn();
            while(!P2&0x02)
              break;
        case 5:
                do
            {
            backward();
            left_turn();//打转}
            while(P2&0x07==0)
            break;
           
        case 6:
   
                do
            rightturn();
            while(P2&0x02)
              break;
        case 7:
   
                do
            forward();
            while(!P2&0x02)
            break;
      }
   }
}
报的错误是：syntax error near ‘break',expected';'