双链表的每个结点包括两个指针域。其中rlink指向结点的后继,llink指向结点的前驱。如果要在p所指结
A) p↑.rlink↑.llink:=q;p↑.rlink:=q;q↑.llink:=p;q↑.llink:=p↑.rlink;
B) p↑.llink↑.rlink:=q;p↑.llink:=q;q↑.llink:=p;q↑.llink:=p↑.llink;
C) q↑.llink:=p;q↑.rlink:=p↑.rlink;p↑.rlink↑.llink:=q;p↑. rlink:=q;
D) q↑.rlink:=p;q↑.llink:=p↑.llink;p↑.llink↑.rlink:=q;p↑.llink:=q;