void Sort(CList &stulist)
{
 CNode *p1,*p2,*p3,*big;
 for(p1=stulist.get_listhead();p1!=NULL;p1=p1->pnext)
 {
big=p1;
p2=p1->pnext;
while(p2)
{
     if(big->pdata->get_score()<p2->pdata->get_score())
      big=p2;
 p2=p2->pnext;
......................