请问错在哪里 ，一直编译运行有错

#include <iostream>
using namespace std;
int main ()
{ int score;
  int scorephrase;
  cout<<"请输入分数\n";
  cin>>score;
  if(score<0||score>100)
  {
        cout<<"此分数不存在"<<endl;
      system("pause");
      return 0;
   }
    scorephrase=score/10;
      switch (scorephrase);
             {  case 10:
                case 9:
                      cout<<score<<"  优"<<endl;
                    break;
                case 8:
                    cout<<score<<"  良"<<endl;
                    break;
                case 7:
                    cout<<score<<"  中"<<endl;
                    break;
                case 6:
                    cout<<score<<" 及格"<<endl;
                    break;
                default:
                    cout<<score<<"  不及格"<<endl;
                    break;
             }
system ("pause");
return 0;
}