在双向指针p的结点前插入一个指针q的结点操作是( )
A.
p->prior=q;q->next=p;p->prior->next=q;q->prior=q;
B.
p->prior=q;p->prior->next=q;q->next=p;q->prior=p->prior
C.
q->next=p;q->prior=p->prior;p->prior->next=q;p->prior=q;
D.
q->prior=p->prior;q->next=q;p->prior=q;p->prior=q;