A.A B.B C.C D.D
A.5:10 B.6:12 C.7:12 D.7:10
A.head->next=p->next;free(p) B.head->next=p;p->next=head->next;free(p) C.free(p);head->next=p;p->next=head->next D.free(p);head->next=p->next
A.a[2][0] B.a[2][1] C.a[2][2] D.a[2][3]