大家好，我碰到个怪问题。。。我有个有个窗体运行一段时间后关闭（this.close()），在下一次加载打开的后（用 FORM1 frm =new FORM1（）），里面的变量居然没有被清空。
我用过this.dispose()，GC.Collect()，甚至在窗体关闭的时候和第二次打开窗体时手动将变量赋空值都试过，都没有用，只要窗体再次打开FORMLOAD完，变量就会继承上一次关闭前的值。请各位高手帮我看看怎么解决这个问题。

  try
                    {
                        for (int i = 0; i < 4; i++)
                        {
                            PC_plan_r[i] = "";
                            PC_PlanName_r[i] = "";
                            DiffCount[i] = 0;
                        }
                        Now_Feed = 0;
                        FeedCount = 0;
                        FeedNum = 0;
                        NowFeeding_IsEnd = true;
                    }
                    catch (Exception ex)
                    {
                        MessageBox.Show(ex.ToString());
                    }
                    xmlfrm.modifyxml("finishmis",Task.Now_Mission_Num);
                    serialPort1.Close();
                    serialPort2.Close();
                    timer3.Enabled = false;
                    label3.Font = new Font("Arial", 100, System.Drawing.FontStyle.Bold);
                    
                    this.Close();