arraylist重复删除,并两个arrarylist中相同的提取出来．．．．

ArrayList al = new ArrayList();
          al.Add("How");
          al.Add("are");
          al.Add("you!");
          al.Add(100);
          al.Add(200);
          al.Add(300);
          al.Add(1.2);
          al.Add(22.8);
          al.Add("Ho2w");
          al.Add("are");
          al.Add("yo2u!");
          al.Add(1300);
          al.Add(2040);
          al.Add(3200);
          al.Add(1.42);
          al.Add(22.18);
          ArrayList al1 = new ArrayList();
          al1.Add("How1");
          al1.Add("you1!");
          al1.Add("are");
          al1.Add(1001);
          al1.Add(2001);
          al1.Add(3001);
          al1.Add(1.21);
          al1.Add(22.81);
          al1.Add(12);
          al1.Add("How1");
          al1.Add("yasou1!");
          al1.Add("are");
          al1.Add(1001);
          al1.Add(20401);
          al1.Add(35001);
          al1.Add(12.21);
          al1.Add(22.18);
          al1.Add(155);
          ArrayList list = new ArrayList();
          for (int i = 0; i < al.Count; i++)
          {
              for (int j = 0; j < al1.Count; j++)
              {
                  if (al[i].ToString() == al1[j].ToString())
                  {
                      list.Add(al[i]);
                      for (int a = 0; a < list.Count; a++)
                      {
                          for (int l = a + 1; l < list.Count; l++)
                          {
                              if (list[a].Equals(list[l]))
                              {
                                  list.RemoveAt(l);
                                  l--;
                              }

                          }

                      }

                  }
              }
          }
          foreach (object o in list)
          {
              Response.Write(o.ToString());
          }