已知 L 是带表头的,其 P 结点既不是首元结点,也不是尾元结点,删除尾元结点的语句序列是 ( ) ( 1 ) p=p->next; (2) p->next=p; (3)p->next=p->next->next; (4)p=p->next->next; (5)while(p)p=p->next; (6)whlie(Q->next){p=Q;Q=Q->next;} (7)while(p->next!=Q)p=p->next; (8)while(p->next->next!=Q)p=p->next; (9)while(p->next->next)p=p->next; (10)Q=p; (11)Q=p->next; (12)p=L; (13)L=L->next; (14)free(Q);