private void 撤消UToolStripMenuItem_Click(object sender, EventArgs e)

         {

             textBox1.Undo();

         }

         private void 剪切TToolStripMenuItem_Click(object sender, EventArgs e)

         {

             if (textBox1.SelectionLength>)

             {

                 textBox1.Cut();

             }

         }

         private void 复制CToolStripMenuItem_Click(object sender, EventArgs e)

         {

             if (textBox1.SelectionLength > )

             {

                 textBox1.Copy();

             }

         }

         private void 粘贴PToolStripMenuItem_Click(object sender, EventArgs e)

         {

             textBox1.Paste();

         }

         private void 全选AToolStripMenuItem_Click(object sender, EventArgs e)

         {

             textBox1.SelectAll();

         }