帮忙改一下程序（内存泄露？）

template <class Type> void List<Type>::MergeList(List<Type>&Lb,List<Type>&Lc){
 ListNode<Type> *pa,*pb,*pc;
 pa=first->NextNode();
 pb=Lb.first->NextNode();
 Lc.first=pc=first;
 while(pa&&pb){
     if(pa->GetData()<=pb->GetData()){
        pc->link=pa;pc=pa;pa=pa->NextNode();
     }else{
        pc->link=pb;pc=pb;pb=pb->NextNode();
     }
 }
 pc->link=pa?pa:pb;
 delete Lb.first;
}




析构函数是这样的
template <class Type> void List<Type>::MakeEmpty()
{
        ListNode<Type> *q;
        while(first->link!=NULL){
         q=first->link;first->link=q->link;
         delete q;
        }
        last=first;
}
template <class Type> List<Type>::~List()
{
   MakeEmpty();
   delete first;
}