C# 、子窗体调用父窗体属性、方法

 namespace Test
 {
     public partial class FrmMain : Form
     {
         public FrmMain()
         {
              InitializeComponent();
         }
         public DataTable DT;
         private void button1_Click(object sender, EventArgs e)
         {
             FrmChild fm = new FrmOptime(this);
             fm.Show();
          }
         public void BindData(){}
      }
 }

主窗体

 namespace Test
 {
     public partial class FrmChild : Form
     {
         public FrmChild ()
         {
             InitializeComponent();
         }
         FrmMain frmMain;
         public FrmChild (FrmMain fm)
         {
             InitializeComponent();
             frmMain = fm;
         }
     private void button1_Click(object sender, EventArgs e)
     {
         frmMain.RemnantDT;
         frmMain.BindData();
     }
    }
 }

子窗体