C#手动为comboBox添加元素

DataTable iiii = new DataTable();
iiii.Columns.Add("Text");//显示值
iiii.Columns.Add("Value");//实际值
DataRow dr1 = iiii.NewRow();
DataRow dr2 = iiii.NewRow();
dr1["Text"] = "难";
dr1["Value"] = "难";
dr2["Text"] = "易";
dr2["Value"] = "易";
iiii.Rows.Add(dr1);
iiii.Rows.Add(dr2);
comboBox3.DataSource = iiii;
comboBox3.DisplayMember = "Text";
comboBox3.ValueMember = "Value";
comboBox3.SelectedIndex = -1;
           

效果：